General, Technical Data (Refrigerant r134a Servicing - General Information (avant)) Audi A4 B8

A/C SYSTEM AND REFRIGERANT R134A, SAFETY PRECAUTIONS

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Vehicles with Start/Stop System

All vehicles

Note. The refrigerant has a faintly noticeable odor by which it is not recognizable. The refrigerant is heavier than air and falls to lower lying areas such as the work pit, basements, and deep spots and displaces the breathable air and oxygen. Remaining in oxygen deprived areas can be life threatening. Liquid refrigerant, such as, from a leak evaporates at an ambient pressure of approximately 1 bar at roughly -29.4 °C (-20.92 °F). Freezing or frostbite may occur if the refrigerant evaporates onto the skin. Delicate organs, such as, the cornea, are especially at risk. Excessive frostbite may be life threatening. The refrigerant breaks down near flames or when it comes in contact with hot surfaces. There is a danger of becoming poisoned by the resulting toxic fumes if inhaled. A pungent odor indicates that the products of the decomposition mentioned above have already formed. Avoid inhaling these substances under all circumstances, as otherwise the respiratory system, lungs and other organs could be damaged. The specifics associated with the refrigerant, material data etc. can be found in the safety data sheets.

1. Do not attempt repair on filled air conditioning systems by soldering, brazing or welding. This pertains also for welding and soldering work on the vehicle, in the event that parts of the climate control system may heat up When performing paintwork repairs, the temperature in the drying booth or preheating zone must not exceed 80 °C (176 °F).

Reason

Exposure to heat increases the pressure in the system, which could cause the pressure relief valve to open.

Corrective action

Discharge refrigerant circuit using service station.

Note. Always replace damaged or leaking A/C system components. Do not attempt to repair them by soldering, brazing or welding.

Refrigerant vessels (for example, charging cylinders of A/C service station) must never be subjected to excessive heat or exposed to direct sunlight.

Corrective action

Vessels must never be completely filled with liquid refrigerant. Without sufficient room for expansion (gas cushion), vessels will rupture with devastating effect in the event of an increase in temperature. Refer to REFRIGERANT R134A CHARACTERISTICS .

Refrigerant is never to be transferred to systems or vessels in which air is present.

Corrective action

Evacuate systems and vessels before charging with refrigerant.

Vehicle air conditioning systems make use of the vaporization and condensation process. In this case, one works with a substance which boils easily, designated as refrigerant.

The refrigerant employed is tetrafluoroethane R134a, which boils at - 26.5° C (-15.7 °F) at a vapor pressure of 1 bar.

Refrigerant R134a Environmental Information

1. R134a is a fluorocarbon and contains no chlorine.
2. R134a has a shorter atmospheric life span than refrigerant R12.
3. R134a does not damage the ozone layer. The ozone depletion potential is zero.
4. The greenhouse potential of R134a (Global Warming Potential = GWP) is approximately 1300 (the GWP of carbon dioxide = 1).
5. The global warming effect of R134a is "ten" times less than that of refrigerant R12.

Vehicles manufactured after 1992 have air conditioning systems that use refrigerant R134a. This refrigerant does not contain chlorine and does not deplete the ozone layer.

Refrigerant R12 was used through 1992. Due to its chlorine atoms, this CFC has a high potential for depleting the ozone layer as well as a tendency to increase the greenhouse effect.

Conversion programs are available for old existing systems filled with the ozone-depleting substance R12.

For environmental protection reasons, refrigerants must not be released into the atmosphere. For laws and regulations, refer to LAWS AND REGULATIONS .

Refrigerant R134a Physical Data

Critical Point

The critical point (critical temperature and critical pressure) is that above which there is no longer a boundary between liquid and gas.

A substance above its critical point is always in the gaseous state.

At temperatures below the critical point, all types of refrigerant in pressure vessels exhibit both a liquid and a gas phase, for example, there is a layer of gas above the liquid.

As long as both liquid and gas are present in the vessel, the pressure is governed by ambient temperature. Refer to REFRIGERANT R134A VAPOR PRESSURE TABLE .

Note. Different types of refrigerant are never to be mixed. Only the refrigerant designated for the corresponding A/C system may be used.

REFRIGERANT R134A CHARACTERISTICS

The vapor pressure curves of R134a and other refrigerants are sometimes very similar, therefore it is not possible to make a certain distinction solely by pressure.

With R134a, the A/C compressor is lubricated with special synthetic refrigerant oils, for example, PAG oils (polyalkylene glycol oils).

Trade Names and Designations

Refrigerant R134a is currently available under the following trade names

1. H-FKW 134a
2. SUVA 134a
3. KLEA 134a

Note. Different trade names may be used in other countries. Of the wide range of refrigerants available, this is the only one which may be used for vehicles. The designations Frigen and Freon are trade names. They also apply to refrigerants which may not be used in automotive vehicles.

Product Characteristics

Refrigerants used in motor vehicle air conditioning systems belong to the new generation of refrigerants based on chlorine-free, partially fluorinated hydrocarbons (H-FKW, R134a).

With regard to their physical properties, these are refrigerants which have been liquefied under pressure. They are subject to the regulations governing pressure vessels and use is only to be made of approved and appropriately marked containers.

Compliance with specific conditions is required to ensure safe and proper use.

Vapor Pressure

In a partially filled, closed vessel, the quantity of refrigerant evaporating from the surface equals the quantity returning to the liquid state as vapor particles condense. This state of equilibrium occurs under the influence of pressure and is often called vapor pressure. Vapor pressure is a function of temperature. Refer to REFRIGERANT R134A VAPOR PRESSURE TABLE .

Color

Like water, refrigerants are colorless in both vapor and liquid form. Gas is invisible. Only the boundary layer between gas and liquid is visible. (Liquid level in tube of charging cylinder or bubbles in sight glass). Refrigerant R134a fluid may appear colored (milky) in a sight glass. This cloudiness is caused by partially dissolved refrigerant oil and does not indicate a malfunction.

Affect on Metal

In its pure state, refrigerant R134a is chemically stable and does not corrode iron or aluminum.

Refrigerant impurities such as chlorine compounds however cause corrosion of certain metals and plastics. This can lead to blockage, leaks or deposits on the A/C compressor piston.

Critical Temperature/Pressure

The refrigerant R134a remains chemically stable up to a gas pressure of 39.5 bar (corresponding to a temperature of 101° C (214 °F)). Above this temperature, the refrigerant decomposes (refer to "Combustibility").

Water Content

Only very small amounts of water are soluble in liquid refrigerant. On the other hand, refrigerant vapor and water vapor mix in any ratio.

Any water in the refrigerant circuit will be entrained in droplet form once the dryer in the receiver or reservoir has absorbed as little as approximately 7g of water. This water flows as far as the nozzle of the expansion valve or restrictor and turns to ice, the A/C system no longer has a cooling effect.

Water destroys the air conditioner as it combines with other impurities at high pressures and temperatures to form acids.

Combustibility

Refrigerant is non-flammable. It actually has a fire-resistant or fire extinguishing effect. Refrigerant decomposes when exposed to flames or red-hot surfaces. UV light (occurring for example during electric welding) also causes refrigerant decomposition. The resultant decomposition products are toxic and are not to be inhaled. However, irritation of the mucous membranes provides an adequate and timely warning.

Charge Factor

A vessel must have space for vapor as well as liquid. As the temperature rises, the liquid expands. The vapor-filled space becomes smaller. At a certain point, there will only be liquid in the vessel. Beyond this, even a slight increase in temperature causes great pressure to build up in the vessel as the liquid attempts to continue expanding despite the absence of the necessary space. The forces that result are strong enough to rupture the vessel. To prevent a vessel from being overfilled, the regulations regarding compresses gasses specify how many kilograms of refrigerant that may be added to a vessel per liter of interior volume. Multiplying this filling factor with the interior volume gives the permitted filling capacity. The figure for refrigerant used in vehicles is 1.15 kg / liter.

Leak Detection

External damage, for example, can cause a leak in the refrigerant circuit. The small quantity of refrigerant escaping from minor leaks can be detected for example using an electronic leak detector or by introducing a UV-leak detection additive into the refrigerant circuit. Electronic leak detectors are capable of registering leaks with refrigerant losses of less than 5 g per year.

Note. Use leak detectors designed for the type of refrigerant. For example, a leak detector for R12 refrigerant will not work with R134a because R134a refrigerant has no chlorine atoms so the leak detector will not respond to it.

REFRIGERANT R134A VAPOR PRESSURE TABLE

The vapor pressure table for every refrigerant is published in literature for refrigeration system engineers. This table makes it possible to determine the vapor pressure acting on the column of liquid in a vessel if the temperature of the vessel is known.

Because each refrigerant has its own characteristic vapor pressure table, refrigerant can be identified by measuring the pressure and temperature.

Note. At absolute pressure, 0 bar corresponds to absolute vacuum. Normal ambient pressure (positive pressure) equals 1 bar absolute pressure. 0 bar pressure corresponds to an absolute pressure of one bar on most pressure gauges (indicated by -1 bar below 0). Pressure is measured in different units: 1 MPa (mega Pascal) corresponds to 10 bar positive pressure or 145 psi, 1 bar absolute pressure corresponds to 0 bar positive pressure and thus to the ambient pressure (atmospheric pressure).

HANDLING REFRIGERANT

If refrigerant vessels are opened, the contents may escape in liquid or vapor form. This process is intensified the higher the pressure in the vessel.

The pressure level is governed by two factors

1. The type of refrigerant in the vessel. The lower the boiling point, the higher the pressure.
2. The temperature level. The higher the temperature, the higher the pressure.

Protective Eyewear

Put on protective goggles. They prevent refrigerant getting into the eyes, as this could cause severe injury from exposure to cold.

Protective Gloves and Clothing

Greases and oils dissolve readily in refrigerants. They would therefore destroy the protective layer of grease if allowed to come into contact with the skin. Degreased skin is however sensitive to the cold and germs.

Fluid Refrigerant and Skin Precaution

The refrigerant draws heat for evaporation from the surrounding area. Even if this is the skin. This may cause extremely low temperatures. Local frost bite may result (boiling point of R134a: -26.5° C (79.7 °F) at ambient pressure).

Refrigerant Vapor Precaution

If highly concentrated refrigerant vapor escapes, it mixes with the surrounding air and displaces the oxygen necessary for breathing.

Smoking Hazard

A burning cigarette can cause refrigerant to decompose. The resultant substances are toxic and must not be inhaled.

Welding and Soldering on Refrigeration Systems

Before performing welding or soldering work on vehicles in the vicinity of air conditioning system components, extract refrigerant and remove remnants by blowing out with nitrogen.

The products of refrigerant decomposition due to the effect of heat are not only toxic, but may also have a highly corrosive effect on pipes and system components. They mainly take the form of hydrogen fluoride.

Pungent Odor

A pungent odor indicates that the products of decomposition mentioned above have already formed. Avoid inhaling these substances under all circumstances, as otherwise the respiratory system, lungs and other organs could be damaged.

First Aid

1. Following contact with eyes or mucous membranes, immediately rinse with copious amounts of running water and consult an eye specialist.
2. Following contact with the skin, immediately remove affected clothing and rinse skin with copious amounts of water.
3. Following inhalation of highly concentrated refrigerant vapors, immediately take the affected person into the open air. Call a doctor. Administer oxygen in the event of breathing difficulties. If the affected person has difficulty breathing or cannot breathe, tip head back and perform mouth to mouth respiration.

1. Handling Pressure Vessels, refer to «HANDLING PRESSURE VESSELS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__handling-pressure-vessels) .

REFRIGERANT OIL

Refrigerant oil mixes with the refrigerant (about 20-40%, depending on compressor type and amount of refrigerant) and circulates constantly in the system, lubricating the moving parts.

Special synthetic refrigerant oils, such as polyalkylene glycol (PAG) oil, are used in conjunction with R134a air conditioning systems. This is necessary as mineral oil, for example, does not mix with R134a. In addition, the materials of the R134a air conditioning system could be corroded as a result of mixture flowing through the refrigerant circuit under pressure at high temperatures or breakdown of the lubricating film in the compressor. Using non-approved oils can cause the HVAC system to malfunction. Only use approved oils.

Type of oil for R134a in motor vehicles: PAG (polyalkylene glycol) oil

Note. Do not store open containers of refrigerant oil because it attracts moisture. Always keep oil containers sealed. Do not use old refrigerant oil over again. Ester-based oils are only intended for use in large systems, not in passenger vehicle systems. Refrigerant oil characteristics, refer to REFRIGERANT OIL CHARACTERISTICS .

REFRIGERANT OIL CHARACTERISTICS

The most important properties are a high degree of solubility with refrigerant, good lubricity, absence of acid and minimal water content. Only certain oils are permitted. For a list of approved refrigerant oils and capacities, refer to REFRIGERANT OILS .

PAG oils, which are appropriate for refrigerant R134a, are highly hygroscopic and do not mix with other oils. Opened containers should therefore be closed again immediately to prevent ingress of moisture. Moisture and acids promote aging of refrigerant oil, causing it to become dark and viscous as well as corrosive towards metals.

Note. Refrigerant oil, because of its chemical properties, must not be disposed of with engine oils or transmission oils. Only the oil approved for the A/C compressor may be used in refrigerant circuits with refrigerant R134a. Refer to REFRIGERANT OILS .

SAFETY PRECAUTIONS FOR WORKING WITH EXTRACTION AND CHARGING SYSTEM

1. Make sure the shut-off valves are closed before connecting the charging system to the air conditioning system.
2. Before disconnecting the charging system from the air conditioning system, make sure the charging process has been completed to stop refrigerant escaping into the atmosphere.
3. Once the purified refrigerant from the charging system has been transferred to an external compressed-gas cylinder, close the hand shut-off valves at the cylinder and charging system.
4. Do not expose charging system to moisture or use it in a wet environment.
5. Disconnect from power supply before performing service work on the charging system.
6. Never use an extension cable on account of the fire hazard. If the use of an extension cable is unavoidable, the minimum cross-section should be 2.5 mm 2 .
7. In case of fire, remove external cylinder.
8. Entrained oil from the air conditioning system drawn by the suction unit into the measurement vessel supplied is subsequently to be transferred to a sealed container as it contains a small quantity of refrigerant. It must not be released into the environment.
9. Following shutdown, service station is to be secured to stop it rolling away.

HANDLING PRESSURE VESSELS

Secure vessels to prevent them falling over!

Secure upright cylinders to stop them falling over and cylinders lying flat to stop them rolling away.

Do not throw vessels!

If dropped, the vessels could be so severely deformed that they rupture. The refrigerant evaporates immediately, liberating considerable force. Flying fragments of cylinders can cause severe injuries.

To protect the valves, cylinders are only to be transported with protective cap screwed on.

Valves may break off if cylinders are not properly transported.

Never store in the vicinity of radiators.

High temperatures may occur next to radiators. High temperatures are also accompanied by high pressures and the maximum permissible vessel pressure may be exceeded.

Temperature Warning

To avoid possible risk, pressure vessel regulations specify that vessels are not to be heated to in excess of 50° C (122 °F).

Heating Warning

Do not heat with a naked flame under any circumstances. Localized overheating can cause structural changes in the vessel material, which then reduce its ability to withstand pressure. There is also a danger of refrigerant decomposition due to localized overheating.

Empty Containers

Empty refrigerant vessels must always be sealed to prevent the ingress of moisture. Moisture causes steel vessels to corrode. This weakens the vessel walls. In addition, rust particles entering into refrigeration systems from vessels will cause malfunctioning.

SERVICE AND RECYCLING UNITS

At this time, service units for extracting, cleaning and filling refrigerant for motor vehicle A/C systems are available on the market from various manufacturers.

Certain service stations (with appropriate auxiliary device and different adapters if necessary) can also be used for flushing the refrigerant circuit. Refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A .

1. Extraction system group classifications, refer to «EXTRACTION SYSTEM GROUP CLASSIFICATIONS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__extraction-system-group-classifications) .
2. Charging systems not requiring a permit, refer to «CHARGING SYSTEMS NOT REQUIRING A PERMIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__charging-systems-not-requiring-a-permit) .

VEHICLES WITH A/C COMPRESSOR WITHOUT A/C CLUTCH, ONLY WITH A/C COMPRESSOR REGULATOR VALVE

1. The engine can be started only after the refrigerant circuit has been completely assembled (the A/C compressor runs continuously).
2. If the engine has to be operated with the refrigerant circuit empty, only do so for as long as absolutely essential and avoid high engine speeds.

VEHICLES WITH HIGH VOLTAGE SYSTEM

Hybrid vehicles

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

1. The engine may only be started if the refrigerant circuit is completely assembled.
2. Hybrid drive for vehicles with battery cooling is only possible for vehicles with a full A/C system in which there are no stored errors. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C system and the Battery Controls.
3. After the installation of the electrically driven A/C compressor and the subsequent filling of the refrigerant circuit, start up the A/C compressor for the first time using the "compressor intake" function for the basic setting. The A/C compressor may otherwise become damaged if before installation, refrigerant oil was improperly stored in the A/C compressor compression chamber. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for A/C System and Battery Regulator.
4. Only activate the electrically driven A/C compressor when the refrigerant circuits is filled. Damage to the A/C compressor may occur if the A/C compressor is running while the refrigerant circuit is empty. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for A/C System and Battery Regulator.

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

REPAIRING A/C SYSTEM

1. Air conditioning systems designed for refrigerant R12 are only to be filled with refrigerant R134a if certain requirements are fulfilled. Refer to «REFRIGERANT CIRCUIT, CONVERTING R12 TO R134A AND SERVICING»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-converting-r12-to-r134a) .
2. The refrigerant oils specifically developed for R134a and R12 refrigerant circuits are never to be mixed.
3. Service stations which come in contact with the refrigerant are only to be used for the intended refrigerant.
4. Components of R134a refrigerant circuits can be identified by their markings, green labels or design (such as different threads) to prevent interchanging with components designed for refrigerant R12.
5. A label indicating the refrigerant used is provided in the engine compartment on the lock carrier or in the plenum chamber.
6. Different refrigerants are never to be mixed.

Note. When working on the refrigerant circuit, always heed the Safety measures information. Refer to A/C SYSTEM AND REFRIGERANT R134A, SAFETY PRECAUTIONS and REFRIGERANT CIRCUIT PRECAUTIONS .

Special Tools and Accessories

The performance of proper workmanlike repairs on an air conditioning system

1. Requires the use of special tools and materials as listed in «SPECIAL TOOLS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant) .
2. Requires compliance with the basic instructions for use of leak detectors. Refer to «REFRIGERANT CIRCUIT, DETERMINING LEAKS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__refrigerant-circuit-determining-leaks) .
3. Requires expert knowledge.

Note. Environmentally hazardous draining of refrigerant is an offense punishable by law. Refer to LAWS AND REGULATIONS .

LAWS AND REGULATIONS

Note. The laws and regulations listed below are applicable in Germany. Different or additional laws and regulations may apply in other countries.

The effects of climate change can be seen worldwide. Protecting the climate is one of the most important responsibilities. However, this responsibility presents enormous challenges to all involved.

The Kyoto Protocol outlines worldwide goals regarding climate protection, among other things. In addition to target reductions of carbon dioxide, this protocol also outlines target reductions for fluorinated greenhouse gases such as refrigerant R134a due to their high potential of contributing to the greenhouse effect.

Numerous laws have been created for the automotive industry, for example at the European level. For example, chemical-climate protection regulations were put into effect on August 1, 2008 in Germany in order to define the European legislation in more detail.

1. Provision (EU) no. 2037/2000
2. Provision (EU) no. 842/2006
3. Provision (EU) no. 706/2007
4. Provision (EU) no. 307/2008
5. Guideline 2006/40/EU
6. Chemical-climate protection provision, recycling management and disposal regulations (for Germany).

Maintenance and Repair Work On A/C System Refrigerant Circuit

All individuals performing maintenance and repair work on vehicle A/C systems must have completed a training program and be competent in the work required. Other regulations may apply in addition to those of the European Union.

The following general points apply

Operation, repair, decommissioning, take-back obligation

1. When operating, repairing and decommissioning items that contain refrigerant, allowing the refrigerant to vent into the air is prohibited.
2. Keep records on the quantities used during operation and maintenance. A record sheet no longer needs to be kept in the EU due to a provision by the European Parliament in 2005. Other provisions may apply in countries that are not members of the EU.
3. Distributors of the substances and preparations discussed above are obligated to accept these items back after use or to ensure they are accepted by a third party of their choosing.
4. Maintenance and decommissioning of items containing refrigerant that are named in the legislation Substances and preparations named in this legislation may only be accepted by those with the necessary expertise and technical equipment.

Criminal offenses and infringements of the law

1. Willfully or negligently venting refrigerant into the air when operating, repairing or decommissioning items that contain refrigerant constitutes a violation of the laws and legislation described above.

Technical Regulations For Compressed Gases (TRG) 400, 401, 402

Note. The TRG are listed (concerning vehicle manufacturers and workshops) below.

1. TRG 400 (general regulations for charging systems)

Definition of terms and explanatory notes

Charging systems

Charging systems are systems for filling mobile compressed-gas vessels. The charging system includes the premises and facilities concerned.

Charging system requiring permits

Note. Charging systems requiring a permit are ones used to transfer compressed gases to mobile compressed-gas vessels for supplying to third parties. Charging systems not requiring a permit are ones used for transferring compressed gases to mobile compressed-gas vessels for internal use only.

1. TRG 401 (installation of charging systems)

Does not apply to vehicle manufacturers or workshops.

1. TRG 402 (operation of charging systems)

Employees and employee instruction

Note. Employees are to be given instruction on the following topics before beginning work and at regular, appropriate intervals, however at least once a year

1. Hazards specifically associated with handling compressed gases.
2. Safety regulations, particularly the applicable TRG.
3. Procedures in the event of malfunction, damage and accidents.
4. The use of fire-extinguishing and protective equipment.
5. Operation and maintenance of the charging system on the basis of the instructions for use.

Charging systems are only to be operated and maintained by personnel.

Aged 18 and above.

Possessing the necessary technical knowledge.

Who can be relied on to work diligently.

Note. Supervised work may also be performed by personnel that do not meet the requirements stipulated.

Charging (a separate TRG applies to vessels from other countries and their charging).

1. A compressed-gas vessel is only to be filled with the compressed gas declared on it and the quantity must comply with the stipulated pressure, weight or volume data (refer to pressure vessel regulations).
2. In the case of vessels approved for use with several types of compressed gas, the compressed gas with which it is to be filled and - if the compressed gas has a tc > or = -10° C (14 °F) (tc = critical temperature) - the maximum permissible charging weight in line with TRG 104 must be marked on the vessel prior to connection for filling.
3. Compressed-gas vessels marked with the maximum permissible charge pressure in bar at 15° C (59 °F) must be filled manometrically. If, at the time of filling, the temperature is not 15° C (59 °F), the pressure corresponding to the prevailing temperature must be established; it must be ensured that the permissible charge pressure at 15° C (59 °F) is not exceeded in the compressed- gas vessel. The charged vessels are to be checked by way of random pressure measurements to determine possible overfilling.
4. Compressed-gas vessels on which the maximum permissible capacity is indicated by the net weight (filling weight, permissible weight of fill) in kilograms must be filled gravimetrically. The vessels are to be weighed during filling and subsequently subjected to a weight check on special scales to establish possible overfilling. Scales used for this purpose must be calibrated.
5. Under certain conditions, gases with a tc > or = +70° C (158 °F) may be transferred volumetrically from compressed-gas vessels with a maximum volume of 150 l to compressed-gas vessels with a volume of maximum 1000 ccm. The stipulations of the TRG apply to the transfer of liquefied gas to cylinders used by workmen.
6. The following TRG's applies to vehicle vessels

For gases with tk > or = +70° C (158 °F) TRG 101.

Industrial gas mixtures with tk > or = +70° C (158 °F) TRG 102 or TRG 103

Liquefied extremely low-temperature compressed gases (refer to TRG 103) may, contrary to item 4, be filled volumetrically if the charging system and/or the vessels is/are equipped with devices for measuring or limiting the volume of the charge and - with the exception of motor vehicle vessels as per item 3 - for measuring the temperature of the charge. When filling volumetrically, it must be ensured that the permissible charge weight indicated on the vessel is not exceeded. To determine possible overfilling, the filled containers are to be checked gravimetrically on a calibrated scale or - provided that the pressurized gases are not highly toxic - volumetrically. Volumetric checking requires the use of appropriate equipment. The charging and checking devices must be independent of each other.

1. Charging and check measurements are to be performed by different people. Check measurements must be performed immediately upon completion of the filling process.
2. Overfilled vessels must be drained immediately and in a safe manner until the permissible fill is attained. The compressed-gas fill is then to be determined again.
3. Specific components for the TRG do not or only slightly apply to vessels for liquefied, extremely low-temperature compressed gases which are neither flammable nor toxic; this does not affect the provisions of road traffic legislation.
4. 10. When filling compressed gas vessels with liquefied gases at charging temperatures less than or equal to -20° C, the compressed gas vessel (if the vessel material has not been tested for temperatures less than or equal to -20° C (-4 F)) is not to be released from the charging system for transportation until the vessel wall temperature is greater than or equal to +20° C (68 °F).

Recycling and Disposal Regulations

1. Specifications and rules for handling and disposing of refrigerants and refrigerant oils can be found in the chemical-climate protection provision and recycling and disposal regulations. These are valid in Germany. Different specifications and rules may apply in other countries.

Disposal of Refrigerant

Refrigerants intended for disposal are to be transferred to marked recycling containers, observing the permissible filling quantity. Refer to the chemical-climate protection provision and the recycling and disposal regulations in Germany. Different specifications and rules may apply in other countries.

Disposal of refrigerant oil

Used refrigerant oils from systems employing halogenated hydrocarbons are to be disposed of as waste subject to special supervision. They are not to be mixed with other oils or substances. Proper storage and disposal must be ensured in line with local regulations. Refer to the chemical-climate protection provision and the recycling and disposal regulations in Germany. Different specifications and rules may apply in other countries.

CHARGING SYSTEMS NOT REQUIRING A PERMIT

Charging systems not requiring a permit are ones used for transferring compressed gases to mobile compressed-gas vessels for internal use only.

Note

Some service units are charging systems not requiring a permit. When working with such equipment, the refrigerant is not transferred to mobile compressed-gas vessels, but rather into a permanently installed charging cylinder with visible level gauge and float switch.

Recommendation

It is advisable to use a portable cylinder with visible level gauge and pressure relief valve for surplus refrigerant for internal use.

Attention must be paid to TRG 402 (technical regulations for compressed gases) when transferring compressed gases to other compressed-gas vessels.

EXTRACTION SYSTEM GROUP CLASSIFICATIONS

Note. The service and recycling units used in motor vehicle workshops are extraction and charging systems not requiring a permit (Group 3) but which are only to be operated by qualified personnel. Instructions for unit operation and maintenance can be found in the relevant manufacturer's documentation. Extraction and charging systems of groups 1 and 2 are not used in motor vehicle workshops.

Extraction and Charging Systems Of Group 3

Mobile extraction and charging systems for filling compressed-gas vessels permanently connected to the system.

The refrigerant or refrigerant/oil mixture is transferred to compressed gas vessels which are permanently connected to the mobile systems. In accordance with 3 Para. 5 No. 3 of pressure vessel regulations, compressed-gas vessels are classified as pressure vessels in this case.

The charging systems require

No permit

No expert testing as the gas is transferred to compressed-gas vessels which are classed as being pressure vessels. (Systems used for transfer from these pressure vessels to compressed-gas vessels for supplying to third parties do however require a permit and are subject to mandatory testing).

REFRIGERANT CIRCUIT, CONVERTING R12 TO R134A AND SERVICING

Note. For environmental reasons and on account of the corresponding legislation, refrigerant R12 can no longer be manufactured or supplied. Refrigerant R134a has been developed as a replacement for R12. Air conditioning systems developed and designed for refrigerant R12 cannot however simply be charged with refrigerant R134a. To ensure trouble-free operation of the air conditioning system even after conversion, various components of the refrigerant circuit must be replaced.

REFRIGERANT, KEEPING RECORDS

The environmental statistics law requires records to be kept on the use of refrigerants.

Consequently, motor vehicle workshops may well have to provide the relevant local authorities with information on their use of refrigerant. It is recommended to always keep a record sheet Audi ServiceNet, HSO Environment.

Note. It is recommended to keep a record sheet because the local authorities can request information regarding refrigerant use starting from a certain amount (currently starting with a use of 20 kg in a year). Other provisions may apply in countries that are not members of the EU.

PHYSICAL PRINCIPLES

The four known states of water also apply to air conditioning system refrigerants.

Scheme 266

1. Gaseous (invisible)
2. Vapor
3. Liquid
4. Solid

When water is heated in a vessel (heat absorption), water vapor can be seen to rise. If the vapor is further heated through heat absorption, the visible vapor turns into invisible gas. The process is reversible. If heat is extracted from water in gaseous form -A-, it changes first to vapor -B-, then to water and finally to ice.

Scheme 267

A - Heat absorption

B - Heat emission

Heat Transfer

Every substance consists of a mass of moving molecules. The fast moving molecules of a warmer substance give off some of their energy to the cooler and thus slower molecules. As a result, the molecular motion of the warmer substance slows down and that of the colder substance is accelerated. This process continues until the molecules of both substances are moving at the same speed. They are then at the same temperature and no further heat exchange takes place.

PRESSURE AND BOILING POINT

The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar. If the pressure acting on a fluid changes, its boiling point also changes.

Note. Pressure is measured in different units: 1 MPa (mega Pascal) corresponds to 10 bar positive pressure or 145 psi, 1 bar absolute pressure corresponds to 0 bar positive pressure and thus to the ambient pressure (atmospheric pressure).

Water boils at a lower temperature the lower the pressure.

The vapor pressure curves for water and refrigerant R134a show that, at constant pressure, reducing the temperature changes vapor to liquid (in the condenser) or that reducing the pressure causes the refrigerant to change from liquid to vapor (inside the evaporator).

Vapor Pressure Curve Of Water

Scheme 268

A - Liquid

B - Gas

C - Vapor pressure curve of water

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

Vapor Pressure Curve Of Refrigerant R134a

Scheme 269

A - Liquid

B - Gas

D - Vapor pressure curve of refrigerant R134a

1 - Pressure acting on liquid in bar (absolute)

2 - Temperature in °C

COMFORT

Being comfortable while driving leads to better concentration and safe driving. Air conditioning makes drivers and passengers more comfortable when temperatures or humidity are high. Comfort can of course also be enhanced by opening windows/sun roof or increasing the air output, such a course of action is however associated with certain drawbacks for the occupants of the vehicle, such as more noise, draughts, exhaust fumes and unfiltered pollen (unpleasant for allergy sufferers).

Climate control together with a good heating and ventilation system concept can create a sense of well-being and comfort by regulating temperature, humidity and air circulation in the passenger compartment to suit ambient conditions. This is done both when the vehicle is moving and when it is stationary.

Air conditioning also offers these advantages

1. It cleans the air that enters the vehicle interior. The damp fins on the evaporator collect dust and pollen, which is then removed by condensation.
2. Temperatures in a mid-size vehicle (for example: after a short drive, outside temperature 30° C in the shade and the vehicle exposed to sunlight).

A/C SYSTEM OPERATION

The temperature in the passenger compartment depends on the amount of heat radiated through the windows and conducted by the metal parts of the body. In hot weather it is possible to achieve a more comfortable temperature for the passengers by pumping off some of the heat.

As heat spreads into cooler areas, the passenger compartment is equipped with a unit for generating low temperatures. In the unit, refrigerant is constantly evaporated. The heat required for this is extracted from the air flowing through the evaporator.

After absorbing heat, the refrigerant is pumped off through the compressor. The action of the A/C compressor increases the heat content and temperature of the refrigerant. Its temperature is then substantially higher than that of the surrounding air.

The warm refrigerant flows to the condenser. There, the refrigerant dissipates its heat to the surrounding air via the condenser due to the temperature gradient between the refrigerant and the surrounding air.

The refrigerant thus acts as a heat transfer medium. As it is to be reused, the refrigerant is returned to the evaporator.

For this reason all air conditioning systems are based on the refrigerant circulation principle. There are however differences in the combination of aggregates.

1. Comfort, refer to «COMFORT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__comfort) .
2. Environmental concerns, refer to «REFRIGERANT R134A»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .

REFRIGERANT CIRCUIT PRECAUTIONS

1. Any refrigerant circuit components submitted for quality observation must be sealed (use the caps that come with the replacement part).
2. Replace damaged or leaking components of refrigerant circuit. Refer to «REMOVAL AND INSTALLATION»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant) .

Note. To date, the following replacement parts (A/C compressor, reservoir, evaporator and condenser) are filled with nitrogen gas. This charge is being gradually discontinued. Little or no pressure equalization is therefore noticeable on unscrewing sealing plugs from replacement parts.

1. Workshop-specific instructions .
2. Ensure absolute cleanliness when working.
3. Wear safety goggles and gloves when working with refrigerant and nitrogen.
4. Switch on existing ventilation systems.
5. Use service station to discharge refrigerant circuit, only then open screw connections and replace malfunctioning components.
6. Use a cap to seal off any opened assemblies and hoses to prevent moisture and dirt from getting in.
7. Make exclusive use of tools and materials intended for refrigerant R134a.
8. Seal opened refrigerant oil containers to guard against moisture.

Note. After all engine service work, screw sealing caps (with seals) onto all connections with valve and service connections. Before starting up A/C system, observe vehicle specific filling capacities. Refer to REFRIGERANT R134A CAPACITIES . Do not fill refrigerant, extract refrigerant present and refill the system.

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the "warnings when working on the high voltage system". Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

1. The engine may only be started if the refrigerant circuit is completely assembled.
2. Hybrid drive for vehicles with battery cooling is only possible for vehicles with a full A/C system in which there are no stored errors. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Vehicle Diagnostic Tester in the Function for the A/C system and the Battery Controls.
3. After the installation of the electrically driven A/C compressor and the subsequent filling of the refrigerant circuit, start up the A/C compressor for the first time using the "compressor intake" function for the basic setting. The A/C compressor may otherwise become damaged if before installation, refrigerant oil was improperly stored in the A/C compressor compression chamber. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Vehicle Diagnostic Tester Function for A/C System and Battery Regulator.
4. Only activate the electrically driven A/C compressor when the refrigerant circuits is filled. Damage to the A/C compressor may occur if the A/C compressor is running while the refrigerant circuit is empty. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Vehicle Diagnostic Tester in the Function for A/C System and Battery Regulator.

Charge the vehicle battery using, for example the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Vehicles with Start/Stop System

All vehicles

1. Refrigerant circuit, Cleaning, refer to «REFRIGERANT CIRCUIT, CLEANING»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-cleaning) .
2. Additional notes for vehicles with A/C compressor without A/C clutch (with A/C compressor regulator valve) -N280-). Refer to «VEHICLES WITH A/C COMPRESSOR WITHOUT A/C CLUTCH, ONLY WITH A/C COMPRESSOR REGULATOR VALVE»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__vehicles-with-ac-compressor-without-ac) .
3. O-rings, refer to «O-RING SEALS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__o-ring-seals) .

COMPONENT REPLACEMENT

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Note. Working on the refrigerant circuit with the A/C service station usually requires, although not necessary, the high voltage system to be disabled.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

Vehicles with Start/Stop System

All vehicles

1. All components of the refrigerant circuit submitted for quality observation are always to be sealed (use original sealing caps of replacement part).
2. To date, the following replacement parts (A/C compressor, accumulator, receiver, evaporator and condenser) have been filled with nitrogen gas. This charging stops gradually or the charging pressure is so low that gas does not escape noticeably when opening.
3. On vehicles installed with a compressor with no A/C clutch, the engine is only to be started following complete assembly of the refrigerant circuit (compressor always in operation as well).
4. When the refrigerant circuit is empty, the A/C compressor with A/C compressor regulator valve -N280- (without A/C clutch) is switched to internal lubrication with the result that only a minimal amount of oil is pumped from the compressor into the circuit.

Note. As parts are sometimes stored for lengthy periods and at different locations within the spare parts organization, it is entirely possible that gas will escape from some parts and not from others on initial opening (even in the case of identical spare part numbers). Sealing caps at replacement part connections are therefore to be removed carefully and the nitrogen gas allowed to escape slowly. The refrigerant circuit is equipped either with a restrictor and accumulator or with an expansion valve and receiver. Dryer cartridge or components with desiccant bag (accumulator, receiver) are always to be replaced after cleaning refrigerant circuit (flushing with refrigerant R134a, refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A or blowing through using compressed air and nitrogen REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN ); in doing so, leave sealed as long as possible to minimize absorption of moisture. Dryer cartridge or components with desiccant bag (accumulator, receiver) are to be replaced if required for certain repair operations or if the refrigerant circuit has been open for a lengthy period and moisture has penetrated (such as following an accident). Refer to LEAKING OR DAMAGED COMPONENTS EXCEPT A/C COMPRESSOR, ACCUMULATOR OR RECEIVER - CIRCUIT EMPTY OF REFRIGERANT . The period of time which a refrigerant circuit may be left open without having to replace a component with desiccant bag (accumulator, receiver) depends on ambient influences to a large extent. Given a high ambient temperature and a high humidity level or if the vehicle, for example, has been standing in the open or driven (in wet, foggy weather conditions), the period will be considerably shorter than for a vehicle which has been standing in a heated dry area. The size of the opening through which moisture may enter into the circuit also influences the period for which a refrigerant circuit can be left open without having to replace the component with desiccant bag. Refer to LEAKING OR DAMAGED COMPONENTS EXCEPT A/C COMPRESSOR, ACCUMULATOR OR RECEIVER - CIRCUIT EMPTY OF REFRIGERANT . Seal open connections and pipes (to prevent absorption of moisture). Always replace restrictor.

1. Leaking or damaged components except a/c compressor, accumulator or receiver, refer to «LEAKING OR DAMAGED COMPONENTS EXCEPT A/C COMPRESSOR, ACCUMULATOR OR RECEIVER - CIRCUIT EMPTY OF REFRIGERANT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__leaking-or-damaged-components-except-ac) .
2. Leaking or damaged components except a/c compressor, accumulator or receiver, refer to «LEAKING OR DAMAGED COMPONENTS EXCEPT A/C COMPRESSOR, ACCUMULATOR OR RECEIVER - CIRCUIT CONTAINS REFRIGERANT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__leaking-or-damaged-components-except-ac) .
3. Compressor, replacing without the need for flushing refrigerant circuit, refer to «COMPRESSOR, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__compressor-replacing-without-flushing-refrigerant-circuit) .
4. Compressor, replacing on account of leakage or internal damage, refer to «COMPRESSOR, REPLACING DUE TO LEAKAGE OR INTERNAL DAMAGE»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__compressor-replacing-due-to-leakage-or) .
5. Receiver or accumulator and restrictor, replacing after cleaning refrigerant circuit, refer to «RECEIVER OR ACCUMULATOR AND RESTRICTOR, REPLACING AFTER CLEANING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__receiver-or-accumulator-and-restrictor-replacing)
6. Receiver or accumulator, replacing without the need for flushing refrigerant circuit, refer to «RECEIVER OR ACCUMULATOR, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__receiver-or-accumulator-replacing-without-flushing) .
7. Dryer cartridge / dryer bag, replacing without the need for flushing refrigerant circuit, refer to «DRYER CARTRIDGE AND DRYER BAG, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__dryer-cartridge-and-dryer-bag-replacing) .

CONNECTIONS FOR QUICK-RELEASE COUPLING ON REFRIGERANT CIRCUIT

1. Only valves and connections that are resistant to refrigerant R134a and refrigerant oil must be installed.
2. Different connections (outer diameter) for high pressure and low pressure side.
3. Discharge refrigerant circuit before removing valves or valve inserts.
4. Always screw on sealing caps.

Allocation in the vehicle, refer to Removal and Installation (vehicle-specific repair information).

1. Connections with Schrader valve (needle valve), refer to «CONNECTIONS WITH SCHRADER VALVE»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .
2. Connections with primary sealing valve, (ball valve) «CONNECTIONS WITH PRIMARY SEALING VALVE (BALL VALVE)»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__connections-with-primary-sealing-valve-ball) .

O-RING SEALS

1. Make exclusive use of seals which are resistant to refrigerant R134a and the related refrigerant oils. Color coding of O-rings is no longer employed. Colored and black O-rings are used.
2. Be sure to use seals with the correct inner diameter. Refer to «General Information»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .

1. The O-rings may be used one time only.
2. Coat the seals lightly with refrigerant oil (PAG oil) before installing.

QUICK-RELEASE CONNECTIONS ON REFRIGERANT LINES

Note. This illustration shows a refrigerant pipe with an inner heat exchanger that is installed in the Audi A4 from MY 2008 and on the Audi A5 Coupe from MY 2008. Refer to Removal and Installation (vehicle-specific repair information). The retaining ring -A-, for example, must be opened using the release tool for air conditioner couplings T40149/ in order to remove the refrigerant pipes -D-. Refer to Removal and Installation (vehicle-specific repair information). Replace the quick-release couplings -B- and -G- after removing the refrigerant line with the support ring -E- or -H- and O-ring -F- or -J-. Refer to Removal and Installation (vehicle-specific repair information) .

A - Retaining ring (inside the quick-release coupling, high pressure side)

B - Quick-release coupling with retaining ring (high pressure side)

C - Refrigerant line with an inner heat exchanger

D - Refrigerant line (high pressure side)

E -Support ring (high pressure side)

F - O-ring (high pressure side)

G - Quick-release coupling with retaining ring (low pressure side)

H - Support ring (low pressure side)

J - O-ring (low pressure side)

Note. There are different quick-release coupling versions -A- and -D-. The refrigerant lines -C- can unlocked and removed, for example, using the release tool T40149/1 in the same manner with both versions. The check pins on the -B- quick-release couplings -A- installed at Start Of Production are visible -C-, when the locked refrigerant line -C- is pulled in the direction of arrow. Beginning with MY 2010, as a running change, the quick-release coupling -D- installed and the refrigerant line -C- are being installed in the same manner as the quick-release coupling -A-. If the refrigerant line -C- is pulled in the direction of arrow after assembling, the ring -E- will come out of the quick-release coupling -D- and will show that the retaining ring -F- is completely latched to the refrigerant line -C-. Then the ring -E- can be removed from the refrigerant line -C-.

Scheme 270

1. Different threads for switch on high pressure and low pressure sides.
2. Only valves and O-ring seals that are resistant to refrigerant R134a and refrigerant oil must be installed.

A - Connection (soldered in)

B - O-ring seal

C - Valve (with O-ring seal)

Note. For removing and installing the valve set -B- when the refrigerant circuit is evacuated, for example, use an adapter from the Socket for A/C valves T10364. For the correct tightening specification, refer to CONNECTIONS WITH SCHRADER VALVE .

REFRIGERANT CIRCUIT PIPES AND HOSES

The mixture of refrigerant oil and refrigerant R134a corrodes certain metals (such as copper) and alloys and dissolves some hose materials. Therefore use original replacement parts only.

Pipes and hoses are joined by threaded connections or special plug connectors.

Note. Observe specified torque for threaded connections, use appropriate release tools for plug connectors.

REFRIGERANT CIRCUIT PRESSURES AND TEMPERATURES

The pressures and temperatures in the refrigerant circuit depend on the current operating conditions (such as engine RPM, coolant fan level 1, 2 or 3, engine temperature, A/C compressor on or off) as well as on the effects of outside influences (such as outside temperature, humidity, desired cooling output).

In vehicles with A/C compressor regulator valve -N280-, the pressure is modified on the low pressure side by the A/C compressor regulator valve.

For this reason, values indicated in the following table are valid only as reference points. They are attained at an engine speed of 1500 to 2000 RPM and an ambient temperature of 20° C (68 °F) after about 20 minutes.

The connections for the pressure gauge set intended for the pressure measurement are indicated on the vehicle specific refrigerant circuit. Refer to Diagnosis and Testing (vehicle-specific repair information).

At 20° C (68 °F) with the engine not running, the pressure in the refrigerant circuit is 4.7 bar. Refer to REFRIGERANT R134A VAPOR PRESSURE TABLE .

Note. Pressure is measured in different units: 1 MPa (mega Pascal) corresponds to 10 bar positive pressure or 145 psi, 1 bar absolute pressure corresponds to 0 bar positive pressure and thus to the ambient pressure (atmospheric pressure).

1. Refrigerant Circuit with Expansion Valve, refer to «REFRIGERANT CIRCUIT WITH EXPANSION VALVE, PRESSURES AND TEMPERATURES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-with-expansion-valve-pressures) .
2. Refrigerant Circuit with Restrictor and Reservoir, refer to «REFRIGERANT CIRCUIT WITH RESTRICTOR AND RESERVOIR, PRESSURES AND TEMPERATURES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-with-restrictor-and-reservoir) .

REFRIGERANT CIRCUIT, CLEANING

Flush refrigerant circuit with refrigerant R 134a. Refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A (or with compressed air and nitrogen, 3 REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN ) if

Moisture or dirt has gotten into the refrigerant circuit, for example, after a crash.

Refrigerant oil is dark and viscous.

There is too much refrigerant oil in the refrigerant circuit after replacing the compressor.

The A/C compressor had to be replaced due to internal damage (for example, noises or no output).

Note. When flushing components with compressed air and nitrogen, always extract the gas mixture escaping from the components with suitable extraction units (workshop extraction system).

REFRIGERANT CIRCUIT, FLUSHING

Note. In the case of vehicles on which the refrigerant pipes have no threads for connection of Adapter set -1785-, use, for example, a flushing gun with rubber end piece or an adapter from the Adapter case for VW/Audi passenger cars VAS 6338/1 for blowing through the individual components. When using a flushing gun with rubber end piece, take special care not to damage the connections (crushing or scratching). Evaporator is to be flushed via the connection for low-pressure pipe (large diameter) after removing expansion valve or removing restrictor. Always flush components in direction opposite to refrigerant flow. Check expansion valve and replace if dirty or corroded. Replace any components on which dark, sticky deposits cannot be removed with compressed air. Flush these components using refrigerant R134a or replace. Thin, light grey deposits on the insides of pipes do not impair the function of the components. After flushing, always replace receiver or reservoir and restrictor. Replace dryer cartridge on condensers with dryer. If the reservoir / dryer cartridge is integrated in the condenser, then they cannot be replaced individually and the condenser must be replaced. Refer to and Removal and Installation . Reservoirs, where it is possible to replace the dryer cartridge, have an additional filter, which must also be replaced with the dryer cartridge.

After Blowing Through The Refrigerant Circuit

Replace these components depending on equipment (restrictor and reservoir, expansion valve and fluid reservoir or dryer cartridge). Refer to Removal and Installation (vehicle-specific repair information) .

Replace the A/C compressor, depending on its condition. Refer to Removal and Installation (vehicle-specific repair information) or drain the rest of the refrigerant oil still inside the removed A/C compressor REMOVAL AND INSTALLATION and fill with new refrigerant oil. Refer to REFRIGERANT OIL CAPACITIES .

Note. There is a defined and prescribed amount of refrigerant oil in the replacement compressor. If the vehicle has two evaporators, then there refrigerant circuit requires a specific quantity of refrigerant oil. Refer to Removal and Installation (vehicle-specific repair information) and REFRIGERANT OIL CAPACITIES . If the A/C compressor is not be replaced, the quantity of refrigerant oil in the A/C compressor must be topped off to the prescribed capacity (tilt the refrigerant oil out and refill the prescribed quantity into the A/C compressor or refrigerant circuit). Refer to REMOVAL AND INSTALLATION and REFRIGERANT OIL CAPACITIES .

Reassemble the refrigerant circuit completely. Refer to Removal and Installation (vehicle-specific repair information).

Evacuate and recharge refrigerant circuit according to specification. Refer to EVACUATING REFRIGERANT CIRCUIT and CHARGING REFRIGERANT CIRCUIT .

Start up A/C system according to specification. Refer to Removal and Installation and A/C SYSTEM, OPERATING AFTER CHARGING .

REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Note. Working on the refrigerant circuit with the A/C service station usually requires, although not necessary, the high voltage system to be disabled.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

All vehicles

Compressed air and nitrogen are to be used in order to force out moisture and other contaminants as well as old refrigerant oil as efficiently as possible, without wasting refrigerant. Clean refrigerant circuit (flush with refrigerant R134a or blow through with compressed air and nitrogen).

Note. For the most part, blowing through the refrigerant circuit with compressed air and nitrogen requires significantly more work than flushing with refrigerant R134a. As flushing with refrigerant R134a cleans the components more efficiently, always flush in case of a complaint (blowing through should only be used for certain complaints and individual components). Under certain conditions it may be sufficient to blow through certain components (such as individual refrigerant lines or refrigerant hoses) with compressed air and nitrogen (for purposes of forcing out old refrigerant oil from individual components that were removed). Certain contaminants cannot or can only be insufficiently removed from the refrigerant circuit with compressed air, these contaminants can be removed, for example by flushing with refrigerant R134a. Refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A . When blowing through, the maximum work pressure of 15 bar must not be exceeded (corresponding to pressure that is reached in a filled refrigerant circuit with an ambient temperature of approximately 60° C (140 °F), if necessary use pressure reducer also for compressed air).

Always flush components in direction opposite to refrigerant flow.

Note. Restrictor, expansion valve, compressor, receiver and reservoir cannot be flushed with compressed air and nitrogen.

Remove dryer cartridge on condensers with dryer.

Note. If the reservoir / dryer cartridge is integrated in the condenser, then they cannot be replaced individually and the condenser must be replaced. Reservoirs, where it is possible to replace the dryer cartridge, have an additional filter, which must also be replaced with the dryer cartridge.

First flush out old refrigerant oil and dirt using compressed air and then use nitrogen to remove component moisture.

Adapter for sealing off the pressure hose to the refrigerant circuit, refer to A/C SERVICE STATION .

Note the following points to prevent oil and moisture from entering the refrigerant circuit from the compressed air system.

The compressed air must be routed through a compressed air purifier for cleaning and drying. Use is therefore to be made of filter and dryer for compressed air (included in scope of delivery as tool for painting work).

On refrigerant lines with thread or union nut on the connection, use adapter from Adapter set V.A.G 1785 (Adapter V.A.G 1785/1 to Adapter V.A.G 1785/8) to connect charge hoses 5/8" -18 UNF (a section of this adapter is also contained in the VW/Audi passenger vehicle set adapter chest VAS 6338/1).

On refrigerant lines without thread or union nut on the connection (for connecting adapters), use adapter from VW/Audi passenger vehicle set adapter chest VAS 6338/1 or a standard blower pistol with rubber mouthpiece.

Note. Only blow through refrigerant circuit with compressed air and then with nitrogen if there is no possibility of flushing the refrigerant circuit or the amount of work to flush individual components becomes excessive (such as minor contaminants and moisture can also be blown out of the refrigerant lines in a short period of time). Compressed air/nitrogen emerging from components is to be drawn off by way of an appropriate system (such as workshop extraction system).

The circuit (or individual components) must be blown through (if there is no possibility for flushing or flushing is not recommended)

In the event dirt or other contaminants are located in individual components of the circuit.

If vacuum reading is not maintained on evacuating a leak-free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit).

If refrigerant circuit has been left open for longer than normal (such as following an accident).

Pressure and temperature measurements in the refrigerant circuit indicate the likelihood of moisture.

In the event of doubt about the amount of refrigerant oil in the circuit.

The A/C compressor had to be replaced on account of internal damage (such as noise or no output).

If stipulated by the vehicle-specific repair information following replacement of certain components.

Note. Certain contaminants and old refrigerant oil cannot or can only be insufficiently removed from the refrigerant circuit with compressed air, these contaminants can be removed, for example by flushing with refrigerant R134a. Refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A .

1. Refrigerant Circuit, flushing, refer to «REFRIGERANT CIRCUIT, FLUSHING»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-flushing) .

REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Note. Working on the refrigerant circuit with the A/C service station usually requires, although not necessary, the high voltage system to be disabled.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

All vehicles

Note. Audi does not approve the use of chemicals to seal leaks in the refrigerant circuit (leak stop additives). Chemical materials to seal leaks in the refrigerant circuit react with air or the moisture in the air and form deposits in the refrigerant circuit and the A/C service station that lead to malfunctions in the valves and other components that come into contact with such chemicals. These deposits cannot be removed completely from the components, even by flushing. It is only possible to service the refrigerant circuit by replacing all the components which come in contact with this material. It is not possible to recognize chemical substances to seal leaks in the refrigerant circuit (leak stop additive) and the label that is supposed to come with them is usually not there. Therefore be careful when working with if you do not know its service history.

1. Refrigerant circuit must be flushed with refrigerant R134a in order to force out moisture and other contaminants as well as old refrigerant oil as efficiently as possible, without wasting refrigerant, without the need for extensive assembly work and without endangering the environment.

Flush The Refrigerant Circuit

In the event of dirt or other contamination in the circuit.

If vacuum reading is not maintained on evacuating a leak-free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit).

If refrigerant circuit has been left open for longer than normal (such as following an accident).

Pressure and temperature measurements in the refrigerant circuit indicate the likelihood of moisture.

In the event of doubt about the amount of refrigerant oil in the circuit.

The A/C compressor had to be replaced on account of internal damage (such as noise or no output).

If stipulated by the vehicle-specific repair information following replacement of certain components.

Tools Required

1. A/C service station with flushing device (on these A/C service stations, the auxiliary function "flush refrigerant circuit" and the refrigerant circuit flushing device required for it are present on these A/C service stations.
2. VW/Audi passenger vehicle set adapter chest VAS 6338/1. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit)

Note. If a A/C service station with flushing device is not available, it is possible to flush the refrigerant circuit with the flushing device available using Refrigerant circuit flushing device, however the flushing must be done manually. Refer to REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A => Sequence of Flushing Procedure (sequence occurs automatically according to the A/C service station program) . On vehicles with screw connections on refrigerant circuit, Adapter V.A.G 1785/7 and Adapter V.A.G 1785/8 from VW/Audi passenger vehicle set adapter chest VAS 6338/1 can be used; on vehicles with screw connections at A/C compressor and at reservoir, two Adapters V.A.G 1785/8 are required. In VW/Audi passenger vehicle set adapter chest VAS 6338/1, there is also a Charge hose VAS 6338/31 with connections 5/8 -18 UNF and large inner diameter in short version (commercially available).

Preparation

Discharge refrigerant circuit. Refer to DRAINING REFRIGERANT CIRCUIT .

Remove the A/C compressor. Refer to Removal and Installation (vehicle-specific repair information).

On a vehicle with restrictor and reservoir

Remove restrictor (vehicle-specific) and reconnect lines. Refer to Removal and Installation (vehicle-specific repair information).

Remove reservoir (vehicle-specific) and reconnect the lines (use adapters and Fill hose VAS 6338/31 from the Adapter case for VW/Audi passenger cars VAS 6338/1). Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT , Removal and Installation (vehicle-specific repair information).

Note. The reservoir could be flushed but because of its large internal volume it will take too much refrigerant, the reservoir would ice-up too much when extracting the refrigerant, the refrigerant would evaporate too slowly and extraction would be extended too much.

On a vehicle with expansion valve and fluid reservoir

Remove fluid reservoir (vehicle-specific) and reconnect the lines (use adapters and Fill hose VAS 6338/31 from the Adapter case for VW/Audi passenger cars VAS 6338/1). Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT , Removal and Installation (vehicle-specific repair information).

Note. The fluid reservoir can be flushed depending on the version (remove dryer cartridge if necessary). Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT , Removal and Installation (vehicle-specific repair information). The fluid reservoir connected to the condenser (such as on model Audi A3 from model year 2004) remains installed during flushing (it can be flushed due to its design and is only replaced after flushing). Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT and Removal and Installation (vehicle-specific repair information). If the reservoir / dryer cartridge is integrated in the condenser, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Replace the condenser with the reservoir on these vehicles. Refer to Removal and Installation Reservoirs, where it is possible to replace the dryer cartridge, have an additional filter, which must also be replaced with the dryer cartridge.

Remove dryer cartridge from vehicles with dryer partridge in fluid reservoir that is connected to the condenser (vehicle-specific), and seal opening on fluid reservoir. Refer to Removal and Installation (vehicle-specific repair information).

Remove expansion valve (vehicle-specific) and install one adapter from the Adapter case for VW/Audi passenger cars VAS 6338/1. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT , Removal and Installation (vehicle-specific repair information).

Note. If there is no adapter suitable for the expansion valve in the VW/Audi passenger vehicle set adapter chest VAS 6338/1, the removed expansion valve can also be drilled open (the old expansion valve must be replaced in most cases and is therefore no longer required).

Note. Before drilling open, remove the regulating element and drill open the expansion valve using a suitable drill (drill bit diameter 6.0 mm). Several components are to be removed from expansion valve before drilling open. Expansion valves are available in various versions and with different constructions. For version -A-, for example, parts -B-, -C- and -D- must be removed. Then separate part -E- (regulating element) from component -D-. Then drill open expansion valve in area -F- using a suitable drill. For version -G-, for example parts -H-, -I- and -K- must be removed and then drill open area -L- using a suitable drill.

Clean the drilled open expansion valve of residue from the work (shavings).

Install parts -B-, -C- and -D- for version -A- or -H- for version -G-.

Note. On vehicles with two evaporators, disconnect second evaporator circuit from first evaporator circuit and flush separately. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT and Removal and Installation (vehicle-specific repair information).

Flushing

Check refrigerant quantity in the A/C service station, there must be at least 7 kg of refrigerant R134a.

Note. If necessary, switch on heating installed in service station for the refrigerant container before first flushing (to increase the pressure in the refrigerant container) and switch off before first extraction during flushing.

Drain the old oil container of the A/C service station

Connect the supply hose (high pressure side) of A/C service station to the low pressure line leading to the A/C compressor (line with larger diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

Connect return hose (low pressure- or intake side) of A/C service station to output of refrigerant circuit flushing device.

Connect the input on the refrigerant circuit flushing device to the high pressure line leading to the A/C compressor (line with smaller diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

Note. Components are always flushed in the opposite direction of refrigerant flow when A/C system is in operation. Refer to FLUSHING CIRCUIT BLOCK DIAGRAMS . While flushing, contaminants from the refrigerant circuit enter the refrigerant circuit flushing device and the A/C service station and are absorbed by the filters and dryers installed there. Depending on the contaminant, these components are to be replaced in shorter intervals in line with operating instructions for A/C service station or refrigerant circuit flushing device. The filter in the refrigerant circuit flushing device depends on the type and degree of contamination in the flushed refrigerant circuit, it should be changed after 5 to 10 flushing cycles (flushed vehicles) at the latest. If a heavily contaminated refrigerant circuit is flushed (the refrigerant oil from the circuit is black and viscous or there are many shavings in the refrigerant circuit), the filter should be replaced after flushing. With a refrigerant circuit heavily contaminated in this way, it is wise to flush the circuit again after changing the filter. Depending on the type of contamination, dirt (old refrigerant oil and abraded material from A/C compressor) is deposited on the viewing glass. Clean this viewing glass if necessary after flushing and flush the refrigerant circuit once more with a flushing operation as a test (one completed cycle is sufficient). Liquid refrigerant cannot be led through the expansion valve, restrictor and dryer bag of certain fluid reservoirs at an appropriate speed, therefore these components must be removed and replaced by adapters if necessary. Refer to Removal and Installation (vehicle-specific repair information). Adapters for connecting A/C service station and for bridging certain components of refrigerant circuit, refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

Switch on A/C service station and flush refrigerant circuit (duration approximately 1 to 1.5 hours for one flushing cycle with three flushing operations).

Note. Perform flushing procedure according to operating instructions of the A/C service station. Depending on version of A/C service station, old oil container holds only approximately 125 cm 3 refrigerant oil, in the event a system with a larger quantity of refrigerant oil must be flushed, it may be necessary to drain the old oil container after the first flushing process of one flushing cycle. Observe the refrigerant which flows back into the A/C service station from the refrigerant circuit, only when the refrigerant streams clear and completely colorless through the viewing glass of refrigerant circuit flushing device into the A/C service station is the refrigerant circuit cleaned. While flushing, all the refrigerant oil is washed out of the refrigerant circuit (up to a very small amount, for example, in the evaporator, however this can be disregarded). If contamination is especially severe, it may be necessary to perform the flushing procedure twice (two flushing cycles with three flushing operations each).

SEQUENCE OF FLUSHING PROCEDURE (SEQUENCE OCCURS AUTOMATICALLY ACCORDING TO THE A/C SERVICE STATION PROGRAM)

1. After switching on, the flushing circuit (refrigerant circuit with connecting hoses and flushing equipment for refrigerant circuits) is evacuated first and the refrigerant circuit is checked for leaks during this. (depending on A/C service station version, it is possible that manually switching to advance the program is required).
2. A prescribed quantity of refrigerant (such as 5 kg) is filled into the evacuated refrigerant circuit via the high pressure side of the A/C service station (in opposite direction of normal flow when A/C system is in operation and also on the low pressure side of the vehicle refrigerant circuit), or, as much refrigerant is filled until refrigerant circuit and viewing glasses of refrigerant circuit flushing device are completely filled with fluid refrigerant (depending on version of A/C service station, recognized, that is, that refrigerant no longer flows from behind over a certain time period).
3. After the prescribed quantity of refrigerant has been filled, for example, the heater for the refrigerant circuit flushing device is switched on (only in the event the refrigerant is extracted in gaseous form from the refrigerant circuit flushing device), depending on version of A/C service station and refrigerant circuit flushing device.
4. After the refrigerant was extracted, the heating of the flushing device for refrigerant circuits is switched off (if present), it may occur that the refrigerant circuit is shortly evacuated again, depending on its version. After evacuation, the refrigerant extracted from the refrigerant circuit is deposited by the service station.
5. The sequence of filling refrigerant, extracting (and evacuating) is repeated twice (performed a total of three times).
6. After the third extraction, the flushing circuit is evacuated depending on the version of the A/C service station.

After the flushing procedure has ended, check the viewing glass(es) of refrigerant circuit flushing device, if they are soiled, clean them if necessary according to operating instructions of the refrigerant circuit flushing device or of the A/C service station and perform the flushing procedure once more as a test (one cycle is sufficient, duration approximately 30 min.)

Check pressure in refrigerant circuit, there must be no positive pressure in the refrigerant circuit (evacuate briefly once more if necessary).

Disconnect connections to A/C service station from vehicle refrigerant circuit (there must be no positive pressure in the refrigerant circuit).

Replace these components depending on equipment (restrictor and reservoir, expansion valve and fluid reservoir or dryer cartridge inside the reservoir). Refer to Removal and Installation (vehicle-specific repair information) .

Replace the A/C compressor, depending on its condition, refer to Removal and Installation (vehicle-specific repair information) or drain the rest of the refrigerant oil still inside the removed A/C compressor, refer to REMOVAL AND INSTALLATION and fill new refrigerant oil. Refer to REFRIGERANT OIL CAPACITIES .

Note. There is a defined and prescribed amount of refrigerant oil in the replacement compressor. If the vehicle has two evaporators, then there refrigerant circuit requires a specific quantity of refrigerant oil. Refer to Removal and Installation (vehicle-specific repair information) and REFRIGERANT OIL CAPACITIES . If the A/C compressor is not be replaced, the quantity of refrigerant oil in the A/C compressor must be topped off to the prescribed capacity (tilt the refrigerant oil out and refill the prescribed quantity into the A/C compressor or refrigerant circuit). Refer to REMOVAL AND INSTALLATION and REFRIGERANT OIL CAPACITIES .

Reassemble the refrigerant circuit completely. Refer to Removal and Installation (vehicle-specific repair information).

Evacuate and recharge refrigerant circuit according to specification. Refer to EVACUATING REFRIGERANT CIRCUIT and CHARGING REFRIGERANT CIRCUIT .

Start up A/C system according to specification. Refer to Removal and Installation and A/C SYSTEM, OPERATING AFTER CHARGING .

1. Flushing Circuit Block Diagrams, refer to «FLUSHING CIRCUIT BLOCK DIAGRAMS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__flushing-circuit-block-diagrams) .
2. Adapter for Assembling Flushing Circuit, refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) .
3. Rinse the electrically driven A/C compressor (remove the refrigerant oil), refer to «ELECTRICALLY DRIVEN A/C COMPRESSOR, RINSING (REMOVE REFRIGERANT OIL)»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__electrically-driven-ac-compressor-rinsing-remove) .

REFRIGERANT CIRCUIT, REPAIRING

The purpose of this Repair Information is to provide foremen and mechanics with the basic knowledge needed to ensure expert working.

Note. Only the careful study of this documentation, practical implementation of the information contained, a training on A/C systems and expert knowledge (with or without certificate) can guarantee expertise in the field of motor vehicle A/C systems.

This document is a compact reference work which should be kept at the workplace. It should also be available for presentation to the responsible supervisory agency on request.

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES

Vehicles with Start/Stop System

All vehicles

Additional Information Sources

1. Repair information for model-specific maintenance, refer to «General Information»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information) and refer to the appropriate SYSTEM WIRING DIAGRAMS information.

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

SWITCHES AND SENSORS

Note. Switch pressures, removing and installing switches as well as switch arrangement and version, refer to vehicle specific refrigerant circuit. Refer to Removal and Installation .

ELECTRICALLY DRIVEN A/C COMPRESSOR, RINSING (REMOVE REFRIGERANT OIL)

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

Rinse the A/C compressor

Note. The refrigerant oil cannot be poured out for electrically driven A/C compressors (there is no oil drain plug) nor can it be poured out during the removal of the compressor. The refrigerant oil is removed by rinsing in the flow direction for electrically driven A/C compressors (it is impossible to rinse against the flow direction because of the installed valve). To rinse, set up the A/C compressor so that the connection for the refrigerant line on the high pressure side is as low as possible.

Scheme 271

1. A/C Service Station With electronics and a flushing program, A/C service station with flushing device. If an A/C service station without a flushing program is used, the procedure must be performed manually (evacuate, flush 3 times with at least 2 kg refrigerant each and extract refrigerant again, evacuate).
2. Refrigerant Hose of A/C Service Station From high pressure side of A/C service station (mostly colored red) to low pressure side connection of A/C compressor on refrigerant circuit (larger diameter).
3. Adapter to the Connection For the Low Pressure Side On the A/C Compressor Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) From VW/Audi passenger vehicle set adapter chest VAS 6338/1
4. Refrigerant Line To the A/C compressor connection on the adapter, item 3 3 To remove the rinse circuit, for example, remove the refrigerant lines to the condenser from the vehicle (or use a refrigerant line with the part number 7L6 820 744 AD).
5. Electrically Driven A/C Compressor The A/C compressor is rinsed in the flow direction (from the entrance on the low pressure side to the exit on the high pressure side) So that as much of the refrigerant as possible is rinsed out from the A/C compressor, the A/C compressor must be positioned so that the exit on the high pressure side is as low as possible
6. Refrigerant Line To the A/C compressor connection on the adapter, item 7 7 . To install the rinse circuit use for example a refrigerant line with the part number 7L6 820 721 BF or 4G0 260 701 AB.
7. Adapter to the Connection For the High Pressure Side On the Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1
8. Charge Hose For Refrigerant Circuit Flushing Device From connection to the high pressure side of the A/C compressor on the refrigerant circuit (smaller diameter) to input of refrigerant circuit flushing device.
9. Refrigerant Circuit Flushing Device There are different versions of the refrigerant circuit flushing device. With filter, viewing glass, security valve, heater, refrigerant container, etc. (depending on version). Depending on the construction of the A/C service station and of refrigerant circuit flushing device, a check-valve may be installed at output of refrigerant circuit flushing device (to guarantee correct direction of refrigerant flow during flushing).
10. Refrigerant Hose of A/C Service Station From low pressure side of A/C service station (mostly colored blue) to output of refrigerant circuit flushing device.

HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES

Disable The High Voltage System

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

1. Before beginning work on the high voltage system, a high voltage technician must disable the high voltage system. Refer to Disable the high voltage system above. .
2. Use the respective processes for work performed on the high voltage system, for which the system is required to be switched on. For further information about the high voltage system, refer to «HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__hybrid-vehicle-high-voltage-system-procedures) .

Note. Disable the high voltage system before beginning work, for specific work performed on components of the hybrid vehicle which are connected to the high voltage system (such as, to the electrically powered A/C compressor). Work performed on the A/C System, which is not directly affected by the high voltage system (such as, performing a pressure test on the refrigerant circuit, Guided Fault Finding for the A/C system or for the A/C compressor control module -J842- etc.), must only be performed by electrically trained personal. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES and Vehicle Diagnostic Tester "Guided Fault Finding". Disable the high voltage system before beginning work on specific components of the hybrid vehicles, which are located in the vicinity of components belonging to the high voltage system such as, on the battery cooling module, on the expansion valve for the A/C system for the Audi Q5 etc.). Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES and Removal and Installation .

Restart The High Voltage System

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Working On A High Voltage System When Activated Or With Ignition Turned On

Charge the vehicle battery using the Battery charger VAS5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to Battery, Starter, Generator, Cruise Control .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the Instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES

Performing A Visual Inspection

1. Be aware of the power and control electronics for the electrical system, the high voltage cables for the battery and A/C compressor, and the cables for the (electro-drive drive motor) when performing the visual inspection in the engine compartment!
2. Be aware of the high voltage cables and their corresponding covers when performing the visual inspection in the underbody (floor panel)!
3. Be aware during the visual inspection in the rear lid of the hybrid battery, the high voltage cables for the battery and the electronics box with the high voltage system maintenance connector!

Pay attention to the following items when performing a visual inspection

1. The high voltage components do not display any signs of external damage.
2. The high voltage cable insulation must be in tact and the cables are must not be damaged.
3. Look for any abnormal deformations of the high voltage cables.
4. Contact the high voltage technician or the electronics specialist about any abnormalities or uncertainties!
5. Further information about the high voltage system may be in «HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__hybrid-vehicle-high-voltage-system-procedures) .

START/STOP SYSTEM SAFETY PRECAUTIONS

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the "warnings when working on the high voltage system". Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Vehicles with Start/Stop System

All vehicles

1. Refrigerant circuit components, refer to «REFRIGERANT CIRCUIT PRECAUTIONS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-precautions) .
2. For the allocation of the refrigerant circuit components refer to «REFRIGERANT CIRCUIT COMPONENTS, HIGH AND LOW PRESSURE SIDES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-components-high-and-low) .
3. Connections for quick-release coupling on refrigerant circuit, refer to «CONNECTIONS FOR QUICK-RELEASE COUPLING ON REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__connections-for-quick-release-coupling-on-refrigerant) .
4. Refrigerant circuit switches and sensors, refer to «SWITCHES AND SENSORS ON REFRIGERANT CIRCUIT AND CONNECTIONS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .
5. Electrical components not installed in the refrigerant circuit, refer to «ELECTRICAL COMPONENTS NOT ON REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .
6. Refrigerant circuit pressures and temperatures, refer to «REFRIGERANT CIRCUIT PRESSURES AND TEMPERATURES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-pressures-and-temperatures) .
7. Pressure gauge, tests and measurements, refer to «PRESSURE GAUGE, TESTS AND MEASUREMENTS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__pressure-gauge-tests-and-measurements) .
8. Service and recycling units, refer to «SERVICE AND RECYCLING UNITS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__service-and-recycling-units) .
9. Refrigerant circuit repair information, refer to «REPAIRING A/C SYSTEM»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__repairing-ac-system) .

1. Any refrigerant circuit components submitted for quality observation must be sealed (use the caps that come with the replacement part).
2. Replace damaged or leaking components of refrigerant circuit. Refer to «REMOVAL AND INSTALLATION»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant) .

Note. To date, the following replacement parts (A/C compressor, reservoir, evaporator and condenser) are filled with nitrogen gas. This charge is being gradually discontinued. Little or no pressure equalization is therefore noticeable on unscrewing sealing plugs from replacement parts.

A/C COMPRESSOR, MECHANICALLY DRIVEN

The A/C compressor is driven by a ribbed belt or a input shaft, which is driven by the vehicle engine.

Scheme 272

A/C Compressor with Magnetic Clutch

1. An electromagnetic clutch -A- attached to A/C compressor provides the power link between the ribbed belt pulley -B- and A/C compressor crankshaft with A/C system switched on.
2. An overload safeguard attached to the clutch plate or in the A/C compressor solenoid coil is tripped if the compressor does not move freely, thus protecting the belt drive against overload.

A/C Compressor without Magnetic Clutch

1. An overload safeguard attached to the pulley of the compressor -B- is tripped if the compressor does not move freely, thus protecting the belt drive against overload.

All A/C compressors

The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and relays it to the condenser.

Note. The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature. The type plate lists the type of refrigerant required for the A/C compressor. A regulator valve regulates pressure within the specified range (control characteristics) on the low pressure side. A/C compressors with or without a magnetic clutch are currently controlled externally by a regulator valve -C-. On A/C compressors without an A/C clutch, the engine is only to be started following complete assembly of the refrigerant circuit. So that the A/C compressor does not get damaged when the refrigerant circuit is empty, the A/C clutch is turned off and the A/C compressor regulator valve -N280- is no longer activated (A/C compressor runs at idle with engine). If the refrigerant circuit is empty, a A/C compressor without A/C clutch -N25- with (A/C compressor regulator valve -N280-) is switched to internal lubrication by way of a valve. Depending on the A/C compressor version, there may be a valve installed on the high pressure side of the A/C compressor, which prevents the liquid refrigerant from flowing back into the compressor once the A/C is turned off. If an A/C compressor with this valve is installed in a vehicle with a refrigerant circuit having an expansion valve, then it may take some time until the pressure in the high pressure side decreases (the expansion is cold and the pressure in the low pressure side quickly increases after it is turned off, the expansion valve closes and the refrigerant flows slowly into the low pressure side). If the A/C compressor is switched on, the pressure on the low pressure side goes down, the expansion valve open and the refrigerant can flow of the low pressure side. The electro-magnetic clutch -A- is activated only when the regulator valve -C- is activated on an A/C compressor with an electro-magnetic clutch -A- and with a regulator valve -C-. Refer to General Information .

A/C COMPRESSOR, ELECTRICALLY DRIVEN

Hybrid Vehicles

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information .

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Scheme 273

1. The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and relays it to the condenser.
2. The electric motor for the A/C compressor is powered with voltage from the electric drive power and control electronics system -JX1-.
3. The A/C compressor control module -J842- integrated in the A/C compressor controls the rotation and thereby the output for the A/C compressor (electrical A/C compressor -V470-) corresponding with the Data bus receiving requirements. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Control.
4. There is no A/C compressor regulator valve -N280- installed within the electrically driven A/C compressor.
5. Check the bolting points of the A/C compressor and the bracket prior to installation. The contact surfaces must be clean and rust and grease-free. Otherwise, repair the contact surfaces with the contact surface cleaning set VAS 6410. Refer to «General Information»(/audi/a4/b8-2007-2012/remont/wiring-system-data-link-connectors-pwr-dist-grnd-dist/#wiring-general-information-avant) .

Note. Check the amount of the refrigerant oil in the A/C compressor if the A/C compressor control module is faulty. Do not flush the refrigerant circuit with R134a. The A/C compressor control module and the electric A/C compressor -V470- are components and are currently not able to be separated. There is no A/C compressor regulator valve installed in the electrically driven A/C compressor. The power output is regulated externally by the A/C compressor speed sensor. Refer to the appropriate SYSTEM WIRING DIAGRAMS information and Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Controls. The electrically driven A/C compressor functions according to the principle of a spiral charger (similar to a G-charger). The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature. The type plate lists the type of refrigerant required for the A/C compressor. The installed electronics are controlled via the rotation of the A/C compressor power output (and the pressure on the low pressure side) within the designated target areas (control characteristic). The engine should only be started if the refrigerant circuit is completely assembled. The A/C compressor is equipped with a protected oil supply, this prevents A/C compressor damage in the event that the system is empty. This means that approximately 40 to 50 cm 3 of refrigerant oil remains in the A/C compressor. The electrically driven A/C compressor, like the mechanically driven A/C compressor, has a relief valve. Hybrid drive for vehicles with battery cooling is only possible for vehicles with a full A/C system in which there are no stored errors. Refer to Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Controls. After the installation of the electrically driven A/C compressor and the subsequent filling of the refrigerant circuit, start up the A/C compressor for the first time using the "compressor intake" function for the basic setting. The A/C compressor may otherwise become damaged if before installation, refrigerant oil was improperly stored in the A/C compressor compression chamber, refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for A/C System and Battery Regulator. Only activate the electrically driven A/C compressor when the refrigerant circuits is filled. The A/C compressor may become damaged if the A/C compressor is run while the refrigerant circuit is empty. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for A/C System and Battery Regulator.

ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT

1. Various adapters which are required to connect the A/C service station to the refrigerant circuit for flushing and to bridge the removed fluid reservoir or reservoir and expansion valve (specific to vehicle) are in the following table.
2. Using a charge hose with 5/8 -18 UNF connections (short version, for example, Charge hose VAS 6338/31), connect the two adapters (contained in VW/Audi passenger vehicle set adapter chest VAS 6338/1) which have been installed for the removed reservoir or fluid reservoir.
3. If a flushed refrigerant circuit is not reassembled immediately after flushing, adapters remain at connections and seal the connections at the adapters using Shipping caps VAS 6338/30 (from Adapter case for VW/Audi passenger cars VAS 6338/1).
4. Depending on the version of the compressor and time period of production, different connection and sealing techniques can be found for the refrigerant circuit. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .
5. Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.

Block or screw connections

Scheme 274

Screw connection -A

Block connection -B

Block connections with different types of seals

Block connection with radially sealed connection -A- (with plastic or metal guide -B-)

Scheme 275

Block connection with axial sealing connection -C

Audi A3 and Audi TT

Note. The version of the reservoir on the Audi A3 and the Audi TT will different depending on the manufacturer of the condenser. An Audi TT with a 5-cylinder engine has a condenser in a different version than on a model with a 4- or 6-cylinder engine. The reservoir is, for example, inside the condenser. If the integrated reservoir has a dryer cartridge, which is no longer available as a single part. If there are complaints, then it is necessary to replace the complete condenser. Refer to and Removal and Installation . If the reservoir / dryer cartridge is integrated in the condensor, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Refer to Removal and Installation

Audi 80, Audi 90, Audi Coupe, Audi Cabriolet and Audi A4

Note. The reservoir on the Audi A4 (8K_) from MY 2008 has different versions, depending on the depending on the manufacturer. Refer to Removal and Installation . The reservoir may be attached to or integrated in the condenser, depending on the version of the condenser. If the integrated reservoir has a dryer cartridge, which is no longer available as a single part. If there are complaints, then it is necessary to replace the complete condenser. If the reservoir / dryer cartridge is integrated in the condensor, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Refer to Removal and Installation

Audi A5 Coupe and Sportback, Audi Q5, Audi A5 Cabriolet

Note. There are different versions of the reservoir on these vehicles depending on the manufacturer. Refer to Removal and Installation . The reservoir may be attached to or integrated in the condenser, depending on the version of the condenser. If the integrated reservoir has a dryer cartridge, which is no longer available as a single part. If there are complaints, then it is necessary to replace the complete condenser. If the reservoir / dryer cartridge is integrated in the condensor, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Refer to Removal and Installation

Audi Q5 Hybrid

Note. In vehicles with two evaporators, refrigerant circuit is flushed in two / three work steps. Currently the expansion valve on the evaporator in the A/C system and on the evaporator in the battery cooling module have the same connections (only the control characteristics and those on the hybrid battery refrigerant shut-off valve 2 -N517- are different). The refrigerant circuit cannot be rinsed for the one installed in the circuit to the evaporator in the A/C system for a hybrid battery refrigerant shut-off valve 1 -N516-. The hybrid battery refrigerant shut-off valve 1 is in a tight spot and prevents the refrigerant from reaching a sufficient flow speed. In the event that there are two adapters VAG 1785/5 and the hybrid battery refrigerant shut-off valve 1 cannot be drilled, the circuit with the evaporator in the A/C unit can be rinsed using an additional work procedure (reassemble the circuit with a filler hose and two VAG 1785/5). In the event that only one VAG 1785/5i s available and the hybrid battery refrigerant shut-off valve 1 is not drilled, the circuit must be rinsed in two steps. From the low pressure connection on the A/C compressor above the evaporator in the A/C system to the connection for the removed hybrid battery refrigerant shut-off valve 1 and from the connection for the removed hybrid battery refrigerant shut-off valve 1 above the condenser to the high pressure connection on the A/C compressor. There are different versions of the reservoir on these vehicles depending on the manufacturer. Refer to Description and Operation . The reservoir may be attached to or integrated in the condenser, depending on the version of the condenser. If the integrated reservoir has a dryer cartridge, which is no longer available as a single part. If there are complaints, then it is necessary to replace the complete condenser. If the reservoir / dryer cartridge is integrated in the condenser, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Refer to Removal and Installation .

Audi 100, Audi A6 (4A_, 4B_ und 4F_), Audi Allroad and Audi V8

Note. The specifications for the Audi A6 (4F_) from MY 05 also apply to the Audi S6 and Audi RS6.

Audi A6 (4G_), Audi A7 (4G_)

Note. There are different versions of the reservoir on these vehicles depending on the manufacturer. Refer to Removal and Installation . If the reservoir / dryer cartridge is integrated in the condensor, then they cannot be replaced individually or are not available as a single part, and the condenser must be replaced. Refer to Removal and Installation .

Audi A8

Note. In vehicles with two evaporators, refrigerant circuit is flushed in two work steps. Currently the front and rear expansion valves have the same connections (only the control characteristics are different)

Drill an additional hole in the Adapters VAS 6338/5 and VAS 6338/11.

Drill a hole -A- (the dimensions in the illustration are given in mm).

Scheme 276

Rework the Adapter VAS 6338/3.

Sand off or file off the Adapter VAS 6338/3 near -A- without bending the refrigerant pipe (dimensions are in mm).

Scheme 277

Audi Q7

Note. In vehicles with two evaporators, refrigerant circuit is flushed in two work steps.

Audi R8

Note. The A/C compressor can only be removed when the engine is removed on the Audi R8. The refrigerant lines must be removed in order to be able to flush the refrigerant circuit. Refer to Removal and Installation (vehicle-specific repair information). Both installed condensers are flushed in opposite direction of the refrigerant flow direction.

CONDENSER

The condenser conducts heat from compressed refrigerant gas to the ambient air.

Scheme 278

This condenses the refrigerant gas to fluid.

Note. Depending on the version of the refrigerant circuit, the fluid reservoir installed either on the condenser or inside the condenser (integrated). Refer to Removal and Installation (vehicle-specific repair information) .

Scheme 279

1. A- Service connection (soldered in)
2. B- Valve insert (Schrader valve or needle valve)
3. C- O-ring (belonging to the valve)
4. D- Cap with seal

Note. After connecting, install the hand wheel for the service coupling just far enough into the quick-release coupling adapter until the valve is securely opened inside the service connection (pay attention to the pressure gauge, do not put too much pressure on the valve). For removing and installing the valve set -B- when the refrigerant circuit is evacuated, for example, use an adapter from the Socket for A/C valves T10364. Tighten the valve insert -B- very carefully because the tightening specification is very small. There are different versions of these valves, which means there are different tightening specifications. Valve insert -B- with a VG5 (5.2 x 0.7 mm, tire valve) thread has a tightening specification of 0.4 Nm +- 0.1 Nm; a valve insert with a M6 x 0.75 mm thread has a tightening specification of 0.9 Nm +- 0.1 Nm and a valve insert with a M8 x 1.0 mm thread has a tightening specification of 2.0 Nm +- 0.2 Nm. There are different versions of these valves, valve inserts and their caps. Be sure to use the correct version.

CONNECTIONS WITH PRIMARY SEALING VALVE (BALL VALVE)

Connection With High-Pressure Valve

Scheme 280

1. Socket with internal thread (soldered in)
2. O-ring (version and identification: black or colored.
3. Valve with an external thread and groove for the O-ring (identification: ball valve).
4. Cap seal
5. Sealing cap

Note. After connecting, install the hand wheel for the service coupling just far enough into the quick-release coupling adapter until the valve is securely opened inside the service connection (pay attention to the pressure gauge, do not put too much pressure on the valve). For removing and installing the valve -B- when the refrigerant circuit is evacuated, for example, use an adapter from the Socket for A/C valves T10364. There are different versions of these valves (with internal or external threads). The tightening specifications will also differ. The valves -3- with an M12 x 1.5 mm external thread have a tightening specification of 9 Nm +- 1 Nm. There are different versions of these valves, valve inserts and their caps. Be sure to use the right versions.

Connection With Low-Pressure Valve

Scheme 281

1. Socket with an external thread and groove for the O-ring (soldered in).
2. O-ring (version and identification: black or colored.
3. Valve with an internal thread
4. Cap seal
5. Sealing cap

Note. Install the hand wheel for the service coupling just far enough into the quick-release coupling adapter until the valve is securely opened inside the service connection (pay attention to the pressure gauge, do not put too much pressure on the valve). for removing and installing the valve -B- when the refrigerant circuit is evacuated, for example, use an adapter from the Socket for A/C valves T10364. There are different versions of these valves (with internal or external threads). The tightening specifications will also differ. The valves -3- with an M12 x 1.25 mm internal thread have a tightening specification of 9 Nm +- 1 Nm. There are different versions of these valves, valve inserts and their caps. Be sure to use the right versions.

EVAPORATOR

The fluid refrigerant evaporates in the evaporator pipe coils. The heat required for this is extracted from the air flowing on the evaporator ribbing. The air cools off. Refrigerant evaporates and is extracted with the absorbed heat by the A/C compressor.

Scheme 282

A defined amount of refrigerant is supplied to the evaporator by a restrictor or expansion valve. In systems with expansion valve, the throughput is regulated so that only gaseous refrigerant escapes the evaporator outlet.

EXPANSION VALVE

The expansion valve atomizes the streaming refrigerant and controls the flow quantity so that the vapor is gaseous only at the evaporator outlet, depending on the heat transmission.

Scheme 283

Note. Be sure to use the correct part number when replacing the expansion valve. Different characteristic curves matched to the appropriate circuit. Refer to Description and Operation (vehicle-specific repair information). Depending on the A/C compressor version, there may be a valve installed on the high pressure side of the A/C compressor, which prevents the liquid refrigerant from flowing back into the compressor once the A/C is turned off. If an A/C compressor with this valve is installed in a vehicle with a refrigerant circuit having an expansion valve, then it may take some time until the pressure in the high pressure side decreases (the expansion is cold and the pressure in the low pressure side quickly increases after it is turned off, the expansion valve closes and the refrigerant flows slowly into the low pressure side). If the A/C compressor is switched on, the pressure on the low pressure side goes down, the expansion valve open and the refrigerant can flow of the low pressure side.

Scheme 284

1. The expansion valve -A- with the hybrid battery refrigerant shut-off valve 2 -N517- -B- atomizes the streaming refrigerant and controls the flow quantity to the evaporator in the battery cooling module for the hybrid battery unit -AX1- so that the vapor is gaseous only at the evaporator outlet, depending on the heat transmission.
2. If hybrid battery refrigerant shut-off valve 2 -B- is open, it lets refrigerant flow through the expansion valve -A- to the evaporator inside the battery cooling module.
3. The expansion valve -A- and the hybrid battery refrigerant shut-off valve 2 -B- is installed on vehicles with a battery cooling module, and is activated in the A/C system operation, when it is necessary to cool the hybrid battery unit.
4. If the hybrid battery refrigerant shut-off valve 2 -B- is activated by the electronics (for example, from the battery regulation control module -J840-), open it and let the respective refrigerant flow through the control characteristic toward the evaporator in the battery cooling module.
5. The hybrid battery refrigerant shut-off valve 2 -B- attached to the expansion valve -A- is activated, for example, from the battery regulation control module. Refer to the appropriate SYSTEM WIRING DIAGRAMS information and Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Controls.
6. If, for a vehicles with 2 evaporators (one in the A/C unit and one in the battery cooling module), the measured temperature on one of the evaporators corresponds to the target value or the target value falls short, but does not reach the required target value on the other evaporator, the following adjustment is performed: the battery regulation control module activates the electric A/C compressor with increased speed (thereby increasing the A/C cooling output and decreasing the pressure on the low pressure side as well as the evaporator temperature) via the electric drive power and control electronics -JX1- and the A/C compressor control module -J842-. If the target value falls short for the temperature of one of the evaporators, the battery regulation control module activates the hybrid battery refrigerant shut-off valve 1 -N516- or the hybrid battery refrigerant shut-off valve 2, so that the evaporator which is too cold is no longer supplied with refrigerant. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System.

Scheme 285

1. If the hybrid battery refrigerant shut-off valve 1 -A- for the electronics is not activated, open it and let the refrigerant for the evaporator flow into the A/C unit
2. The hybrid battery refrigerant shut-off valve 1 -A- is installed for vehicles with the battery cooling module and is activated in hybrid drive and is necessary for the hybrid battery unit -AX1-, if no A/C system operation is requested for the vehicles interior.
3. Observe the arrow -B- attached to the hybrid battery refrigerant shut-off valve 1 -A- which shows the flow direction of the refrigerant (from the condenser to the evaporator in the A/C unit)
4. The solenoid coil -C- attached to the hybrid battery refrigerant shut-off valve 1 is activated for example, from the battery regulation control module -J840-. Refer to the appropriate SYSTEM WIRING DIAGRAMS information and Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System and the Battery Controls.
5. If, for a vehicles with 2 evaporators (one in the A/C unit and one in the battery cooling module), the measured temperature on one of the evaporators corresponds to the target value or the target value falls short, but does not reach the required target value on the other evaporator, the following adjustment is performed: the battery regulation control module activates the electric A/C compressor with increased speed (thereby increasing the A/C cooling output and decreasing the pressure on the low pressure side as well as the evaporator temperature) via the electric drive power and control electronics -JX1- and the A/C compressor control module -J842-. If the target value falls short for the temperature of one of the evaporators, the battery regulation control module activates the hybrid battery refrigerant shut-off valve 1 or the hybrid battery refrigerant shut-off valve 2 -N517-, so that the evaporator which is too cold is no longer supplied with refrigerant. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for the A/C System.

FLUID RESERVOIR

The receiver collects the fluid drops and then directs them in an uninterrupted stream to the expansion valve. Moisture which has entered the refrigerant circuit during repairs will be collected by the desiccant bag in the receiver.

Scheme 286

Note. Replace the reservoir if refrigerant circuit has been open for a long time (beyond the normal repair time) and moisture has penetrated inside, or if required due to a specific complaint REMOVAL AND INSTALLATION . Only remove sealing plugs shortly before installation. A desiccant bag in an unsealed reservoir is saturated with moisture after a short period of time and unusable. When installing, note arrow for direction of flow if necessary. Depending on the version of the refrigerant circuit, the fluid reservoir installed either on the condenser or inside the condenser (integrated). Refer to Removal and Installation (vehicle-specific repair information) . The procedure is different for each complaint depending on the version of the fluid reservoir and the dryer cartridge. If the fluid reservoir, for example, is attached to the condenser, then it can be replaced complete with the drying cartridge. If the fluid reservoir, for example, is inside the condenser, then the dryer cartridge, and any possible additional filters, can be replaced separately, on most versions. If the fluid reservoir is inside the condenser and there is absolutely no way to replace the reservoir or the dry cartridge individually, then the entire condenser must be replaced. Refer to Removal and Installation (vehicle-specific repair information) . Depending on the construction of the refrigerant circuit, the receiver can also be secured onto the condenser. Refer to Removal and Installation (vehicle-specific repair information) .

FLUSHING CIRCUIT BLOCK DIAGRAMS

Note. The arrows in the following illustrations show the direction of refrigerant flow during flushing (refrigerant flows in opposite direction of flow when A/C system is in operation while flushing, therefore the high pressure side of the A/C service system is connected to the low pressure connection of the refrigerant circuit to the A/C compressor). These block diagrams show a refrigerant circuit with restrictor and reservoir, refer to Refrigerant Circuit with Restrictor and Reservoir and a refrigerant circuit with expansion valve, fluid reservoir and a second evaporator (optional equipment on certain vehicles), refer to Refrigerant Circuit With Expansion Valve, Fluid Reservoir and Second Evaporator . Depending on the construction of the A/C service station, check-valves may be installed between the refrigerant circuit and the A/C service station (to guarantee correct direction of refrigerant flow during flushing).

Refrigerant Circuit with Restrictor and Reservoir

Note. On vehicles with restrictor and reservoir, the restrictor and reservoir are removed, the lines disconnected for removing the restrictor are reconnected again. The connections to the reservoir removed are connected by means of two adapters and the Fill hose VAS 6338/31 (from the Adapter case for VW/Audi passenger cars VAS 6338/1).

Scheme 287

1. A/C Service Station With electronics and a flushing program, for example A/C service station with flushing device. If an A/C service station without a flushing program is used, the procedure must be performed manually (evacuate, flush 3 times with at least 4 kg refrigerant each and extract refrigerant again, evacuate).
2. Refrigerant Hose Of A/C Service Station From high pressure side of A/C service station (mostly colored red) to low pressure side connection of A/C compressor on refrigerant circuit (larger diameter).
3. Adapter To Connection For Low Pressure Side On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
4. Low Pressure Side Connection On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . On refrigerant line from A/C compressor to reservoir.
5. Connection To Reservoir Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . On refrigerant line from A/C compressor to reservoir.
6. Adapter For Bridging The Removed Reservoir Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
7. Refrigerant Charge Hose, refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) Charge hose VAS 6338/31 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1) for example.
8. Adapter For Bridging The Removed Reservoir Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
9. Connection To Reservoir Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) .
10. Evaporator
11. Component Location Of Restrictor Restrictor is removed. Remove the restrictor. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information).
12. Bolts In Refrigerant Line Bolt together again after removing restrictor. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information).
13. Condenser
14. High Pressure Side Connection On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) .
15. Adapter To Connection For High Pressure Side On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
16. Charge Hose For Refrigerant Circuit Flushing Device From connection to the high pressure side of the A/C compressor on the refrigerant circuit (smaller diameter) to input of refrigerant circuit flushing device.
17. Refrigerant Circuit Flushing Device There are different versions of the Refrigerant circuit flushing device. With filter, viewing glass, security valve, heater, refrigerant container, etc. (depending on version). Depending on the construction of the A/C service station and of refrigerant circuit flushing device, a check-valve may be installed at output of refrigerant circuit flushing device (to guarantee correct direction of refrigerant flow during flushing).
18. Refrigerant Hose Of A/C Service Station From low pressure side of A/C service station (mostly colored blue) to output of refrigerant circuit flushing device.

Refrigerant Circuit With Expansion Valve, Fluid Reservoir and Second Evaporator

Note. This block diagram shows a refrigerant circuit with expansion valve, fluid reservoir and second evaporator (optional equipment on certain vehicles). On vehicles with expansion valve and fluid reservoir, the expansion valve is removed and replaced by an adapter. Depending on the vehicle, the fluid reservoir must also be removed and line connections to fluid reservoir be connected to each other by two adapters and a charge hose. On a vehicle with only one evaporator, the components as of position 16 are not installed or are not required.

Scheme 288

1. A/C Service Station With electronics and a flushing program, A/C service station with flushing device. If an A/C service station without a flushing program is used, the procedure must be performed manually (evacuate, flush 3 times with at least 4 kg refrigerant each and extract refrigerant again, evacuate).
2. Refrigerant Hose Of A/C Service Station From high pressure side of A/C service station (mostly colored red) to low pressure side connection of A/C compressor on refrigerant circuit (larger diameter).
3. Adapter To Connection For Low Pressure Side On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
4. Low Pressure Side Connection On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) .
5. Adapter For The Removed Expansion Valve Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1
6. Evaporator
7. Connection To Fluid Reservoir Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . Neither installed on vehicles with dryer cartridge in fluid reservoir at condenser nor with fluid reservoir installed in condenser. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information).
8. Adapter For Bridging The Removed Fluid Reservoir Not required for all vehicles. Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
9. Refrigerant Charge Hose, refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) Charge hose VAS 6338/31 (from VW/Audi passenger vehicle set adapter chest VAS 6338/1) for example.
10. Condenser If a fluid reservoir with dryer cartridge is installed at the condenser, the dryer cartridge must be removed (reseal fluid reservoir at or in condenser). Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information). If the fluid reservoir is directly installed at the condenser, the fluid reservoir must be removed and replaced only after flushing. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) (vehicle-specific repair information). NOTE: On certain vehicles the reservoir is integrated inside the condenser and the dryer cartridge cannot be replaced individually and is not available as a single part. Replace the condenser with the reservoir / dryer cartridge after flushing on these vehicles. Refer to «Removal and Installation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .
11. High Pressure Side Connection On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) .
12. Adapter To Connection For High Pressure Side On Refrigerant Circuit Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
13. Charge Hose For Refrigerant Circuit Flushing Device From connection to the high pressure side of the A/C compressor on the refrigerant circuit (smaller diameter) to input of refrigerant circuit flushing device.
14. Refrigerant Circuit Flushing Device There are different versions of the Refrigerant circuit flushing device. With filter, viewing glass, security valve, heater, refrigerant container, etc. (depending on version). Depending on the construction of the A/C service station and of refrigerant circuit flushing device, a check-valve may be installed at output of refrigerant circuit flushing device (to guarantee correct direction of refrigerant flow during flushing).
15. Refrigerant Hose Of A/C Service Station From low pressure side of A/C service station (mostly colored blue) to output of refrigerant circuit flushing device.
16. Adapter For Sealing Outlet To The Second Evaporator Only necessary on certain vehicles with optional equipment of second evaporator. From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
17. Adapter For Sealing Outlet To The Second Evaporator Only necessary on certain vehicles with optional equipment of second evaporator. From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
18. Low Pressure Side Connection On Refrigerant Circuit To Second Evaporator Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . Only present on certain vehicles with optional equipment of second evaporator.
19. High Pressure Side Connection On Refrigerant Circuit To Second Evaporator Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . Only present on certain vehicles with optional equipment of second evaporator.
20. Adapter For The Removed Expansion Valve On Second Evaporator Different versions depending on vehicle. Refer to «ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__adapter-for-assembling-flushing-circuit) . Only necessary on certain vehicles with optional equipment of second evaporator. From VW/Audi passenger vehicle set adapter chest VAS 6338/1.
21. Second Evaporator Only present on certain vehicles with optional equipment of second evaporator.

These rings seal off the connection points between individual components of the refrigerant circuit.

Scheme 289

Only O-rings that are resistant to refrigerant R134a and refrigerant oil must be installed. Make sure they are original replacement parts.

O-ring seals

Always use only once.

Make sure diameters -a- and -b- are correct.

Coat with refrigerant oil before installing. Refer to Removal and Installation (vehicle-specific repair information).

Note. The color coding of refrigerant circuit O-rings with R134a has been discontinued. Black and colored O-rings are being used. Refer to and General Information (vehicle-specific repair information).

PRESSURE RELIEF VALVE

The pressure relief valve is installed on the A/C compressor or reservoir.

Scheme 290

At a pressure of approximately 38 bar positive pressure, valve opens and closes again once pressure has dissipated (approximately 30 bar).

Refrigerant does not escape completely.

Depending on the version, a transparent plastic disc may be installed which breaks off as soon as the valve is activated.

REFRIGERANT CIRCUIT COMPONENTS, HIGH AND LOW PRESSURE SIDES

High pressure side are the condenser, receiver and restrictor or expansion valve to separate the high and low pressure liquid ends.

High pressure results from the restrictor or expansion valve forming a constriction and causing the refrigerant to accumulate, thus leading to an increase in pressure and temperature.

Excess pressure occurs if too much refrigerant or refrigerant oil is used, the condenser is contaminated, the radiator fan is malfunctioning, the system is blocked or in the event of moisture in the refrigerant circuit (icing-up of restrictor or expansion valve).

Low pressure side are the evaporator, reservoir, evaporator temperature sensor and A/C compressor to separate high and low pressure gas ends.

A drop in system pressure can be caused by loss of refrigerant, the restrictor or expansion valve (no constriction), a malfunctioning A/C compressor or an iced-up evaporator.

1. Mechanically driven A/C compressor, refer to «A/C COMPRESSOR, MECHANICALLY DRIVEN»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__ac-compressor-mechanically-driven) .
2. Electrically driven A/C compressor for hybrid vehicles, refer to «A/C COMPRESSOR, ELECTRICALLY DRIVEN»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__ac-compressor-electrically-driven) .
3. Condenser, refer to «CONDENSER»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__condenser) .
4. Evaporator, refer to «EVAPORATOR»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__evaporator) .
5. Reservoir, refer to «RESERVOIR»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__reservoir) .
6. Restrictor, refer to «RESTRICTOR»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__restrictor) .
7. Fluid reservoir, refer to «FLUID RESERVOIR»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__fluid-reservoir) .
8. Expansion valve, refer to «EXPANSION VALVE»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__expansion-valve) .
9. Refrigerant pipe with inner heat exchanger, refer to «REFRIGERANT PIPE WITH INNER HEAT EXCHANGER»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-pipe-with-inner-heat-exchanger) .
10. Quick-release connections on the refrigerant lines, refer to «QUICK-RELEASE CONNECTIONS ON REFRIGERANT LINES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__quick-release-connections-on-refrigerant-lines) .
11. O-rings, refer to «O-RING SEALS»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .
12. Refrigerant circuit pipes and hoses, refer to «REFRIGERANT CIRCUIT PIPES AND HOSES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__refrigerant-circuit-pipes-and-hoses) .
13. Pressure relief valve, refer to «PRESSURE RELIEF VALVE»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__pressure-relief-valve) .

REFRIGERANT CIRCUIT WITH EXPANSION VALVE, PRESSURES AND TEMPERATURES

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Note. A/C compressors which do not regulate their performance are switched off by the respective control module via the A/C compressor regulator valve -N280- at an evaporator temperature below 0° C (32 °F). In vehicles with A/C compressor regulator valve -N280-, the pressure is modified on the low pressure side by the valve. Temperature and pressure in the refrigerant circuit in vehicles with two evaporators and two expansion valves correspond to those in vehicles with only one evaporator and one expansion valve (parallel switching). Depending on the version of the refrigerant circuit, a component with an inner heat exchanger may be installed (for example, on the Audi A4 from MY 2008 and on the Audi A5 Coupe from MY 2008, a refrigerant line with an inner heat exchanger). Inside the inner heat exchanger, the flowing fluid warm refrigerant on the high pressure side is delivered into the low pressure side as flowing, vapor, cold refrigerant to increase the efficiency of the A/C system. Refer to REFRIGERANT PIPE WITH INNER HEAT EXCHANGER .

Arrows point in direction of refrigerant flow.

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Scheme 291

1. Evaporator
2. Expansion Valve
3. High Pressure Switch / High Pressure Sensor Different versions depending on vehicle
4. Service Connection, HP Side
5. Fluid Reservoir Different versions depending on vehicle
6. Condenser
7. Pressure Relief Valve
8. A/C Compressor, HP side
9. A/C Compressor, LP side
10. Pre-volume Not present on all vehicles
11. Service Connection, LP Side

REFRIGERANT CIRCUIT WITH RESTRICTOR AND RESERVOIR, PRESSURES AND TEMPERATURES

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Pressures on A-side are maintained at approximately 2 bar absolute pressure (corresponds to approximately 1 bar positive pressure) by regulating A/C compressor also at various engine speeds. However, this applies only within the performance range of the A/C compressor; if the performance limits of the A/C compressor are exceeded. Refer to PRESSURES, CHECKING .

Note. In vehicles with A/C compressor regulator valve -N280-, the pressure is modified on the low pressure side by the valve.

Arrows point in direction of refrigerant flow.

HP- High pressure side of refrigerant circuit.

LP- Low pressure side of refrigerant circuit.

Scheme 292

1. A/C Compressor, HP Side
2. Condenser
3. Restrictor
4. Evaporator
5. Reservoir
6. A/C Compressor, LP Side

REFRIGERANT CIRCUIT WITH AN ELECTRICALLY DRIVEN A/C COMPRESSOR (WITH AND WITHOUT BATTERY COOLING MODULE)

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Arrows point in direction of refrigerant flow.

Scheme 293

1. A/C Compressor Driven By Electricity With A/C compressor control module -J842- and electric A/C compressor -V470
2. Condenser With fluid reservoir and dryer cartridge
3. Service Connection, HP Side
4. Hybrid Battery Refrigerant Shut-Off Valve 1 -N516- Only for vehicles with a battery cooling module for the hybrid battery unit -AX1- NOTE: The Hybrid Battery Refrigerant Shut-Off Valve 1 is for example activated, if the battery needs to be cooled and the vehicle interior is not already being cooled (open without activation).
5. Expansion Valve On the evaporator in the A/C system
6. Evaporator Evaporator in the A/C System
7. Expansion Valve With Hybrid Battery Refrigerant Shut-Off Valve 2 -N517- On the evaporator in the battery cooling module Only for vehicles with a battery cooling module for the hybrid battery unit -AX1- NOTE: The Hybrid Battery Refrigerant Shut-Off Valve 2 is activated, if it is necessary to cool the battery (closed without activation).
8. Evaporator Evaporator in the battery cooling module Only for vehicles with a battery cooling module for the hybrid battery unit -AX1
9. Service Connection, LP Side

REFRIGERANT PIPE WITH INNER HEAT EXCHANGER

In this refrigerant pipe, the flowing fluid warm refrigerant on the high pressure side is delivered into the low pressure side as flowing, vapor, cold refrigerant to increase the efficiency of the A/C system.

Scheme 294

Note. This illustration shows a refrigerant pipe with an inner heat exchanger that is installed in the Audi A4 from MY 2008 and on the Audi A5 Coupe from MY 2008. Refer to Description and Operation (vehicle-specific repair information).

A - Refrigerant pipe with inner heat exchanger

B - Channel inside the refrigerant pipe through with the warm fluid refrigerant flows to the evaporator (refrigerant circuit high pressure side)

C - Channel inside the refrigerant pipe in which the vapor of cold refrigerant flow to the A/C compressor (refrigerant circuit low pressure side)

RESERVOIR

The reservoir collects the vaporized and gaseous mixture coming from the evaporator to ensure the compressor only receives gaseous refrigerant. Gaseous refrigerant is formed from the vapor.

Scheme 295

The refrigerant oil flowing in the circuit is not retained in the reservoir as it has an oil drilling.

Moisture which has entered the refrigerant circuit during repairs will be collected by a filter (desiccant bag) in the reservoir.

Gaseous refrigerant is extracted with oil by the A/C compressor.

Note. Replace the reservoir if refrigerant circuit has been open for a long time (beyond the normal repair time) and moisture has penetrated inside, or if required due to a specific complaint. Refer to REMOVAL AND INSTALLATION . Remove sealing plugs -A- and -B- only immediately prior to installing. A desiccant bag in an unsealed reservoir is saturated with moisture after a short period of time and unusable. When installing, note arrow for direction of flow if necessary.

RESTRICTOR

The restrictor creates a constriction. This restriction reduces the flow and creates high and low pressure sides in the refrigerant circuit. Before the restrictor the refrigerant which is under a higher pressure is warm. After the restrictor the refrigerant which is under a low pressure is cold. Before the restriction there is a strainer for contaminants and after the restriction there is a strainer, to atomize the refrigerant before it reaches the evaporator.

Scheme 296

Note. Arrow -A- on restrictor points to evaporator. Replace after each opening of the circuit. There are different versions, therefore pay attention to the different customer service information sources. Refer to Description and Operation (vehicle-specific repair information) .

A/C COMPRESSOR REGULATOR VALVE -N280

The regulator valve is implemented into the compressor. It is controlled by the Front A/C display control head -E87- or the Climatronic control module -J255- (depending on the vehicle, possibly via the databus of the an additional control module). Refer to Description and Operation (vehicle-specific repair information). Pressure on the low pressure side is influenced via the regulator valve and thus regulates the temperature in the evaporator.

Scheme 297

Note. The A/C compressor regulator valve is a component of the A/C compressor and cannot be replaced separately.

Scheme 298

Inductive sensor

The sensor pulses (4 per compressor revolution) and the engine speed enable the Front A/C display control head -E87- or the Climatronic Control Module -J255- to calculate belt slip.

If the belt slip exceeds a specified value, the compressor is switched off by the control module via the A/C clutch.

Note. Installing in Audi vehicles with an A/C compressor driven by a ribbed belt and with Zexel compressor. Refer to Description and Operation (vehicle-specific repair information). Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.

A/C PRESSURE SWITCH -F129

This pressure switch has 3 functions

Scheme 299

1. Switches the coolant fan to the next higher level when the pressure in the refrigerant circuit increases (approximately 16 bar).

2. Switches off A/C system if pressure is excessive (approximately 32 bar), for example, because of insufficient engine cooling.

3. Switches off A/C system if pressure is insufficient (approximately 2 bar), for example, loss of refrigerant.

Note. A/C Pressure Switch -F129- replaces the A/C Refrigerant High Pressure Switch -F23-, A/C Refrigerant Low Pressure Switch -F73- and the A/C Refrigerant High Pressure Switch -F118-.

A/C PRESSURE/TEMPERATURE SENSOR -G395

The A/C pressure/temperature sensor is installed instead of the high pressure sensor -G65- or the refrigerant circuit pressure sensor -G805-.

Scheme 300

The A/C pressure/temperature sensor, the refrigerant circuit pressure sensor and the high pressure sensor are available in different versions. Currently the sensor's only exterior difference is the parts number. Therefore, make sure that the part numbers are correctly allocated when replacing them. Explanation: These sensors produce different signals that can only be identified by the corresponding control modules. Refer to Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" for the A/C system), Description and Operation (vehicle-specific repair information).

When voltage is applied, the A/C pressure/temperature sensor (and the refrigerant circuit pressure sensor -G805- exchange information via the Data bus (for example, via the "LIN-Bus") with the corresponding control module. The relevant control module uses this information to calculate the pressure (and temperature) in the refrigerant circuit and any faults detected are signaled to the control module.

The A/C pressure/temperature sensor transfers the measured values for the pressure in the refrigerant circuit and the measured temperatures to the closed control module. The refrigerant circuit pressure sensor transfers only the measured values for the pressure within the refrigerant circuit for the closed control module. Also if for most vehicles, only the pressure signal is interpreted, no A/C pressure/temperature sensor can or will be installed in a vehicle in which there is a refrigerant circuit pressure sensor.

The temperature measured by the A/C pressure/temperature sensor -G395- differs from the actual refrigerant temperature in the refrigerant circuit because of the A/C pressure/temperature sensor design and its component location. Because of this, it is not currently evaluated and is not used to regulate the A/C system. Refer to Description and Operation (vehicle-specific repair information).

This information is used for example by the Climatronic Control Module -J255- control head or the vehicle electrical system control module -J519- to calculate the pressure in the refrigerant circuit and to actuate the downstream control modules (coolant fan control module, Engine Control Module etc.) via the data bus system. These control modules then regulate, for example the A/C clutch -N25-, the coolant fan and the motor. Refer to the Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" and, Diagnosis and Testing or Description and Operation (vehicle-specific repair information).

Scheme 301

Function

Switches the coolant fan to the next higher level when the pressure in the refrigerant circuit increases (approximately 16 bar).

A/C REFRIGERANT HIGH PRESSURE SWITCH -F118

Function

Switches off A/C compressor when there is excessive pressure in the refrigerant circuit (approximately 32 bar).

Scheme 302

Function

Switches off A/C compressor when there is excessive pressure in the refrigerant circuit (approximately 2 bar).

HIGH PRESSURE SENSOR -G65-, REFRIGERANT CIRCUIT PRESSURE SENSOR -G805

1. This high pressure sensor is installed instead of the A/C pressure switch -F129- or the A/C pressure/temperature sensor -G395-.
2. The refrigerant circuit pressure sensor replaces the high pressure sensor for vehicles from a specific version and from a specific date of manufacture.
3. When a voltage is applied, a version of the high pressure sensor generates a square wave signal or a data telegram. This signal changes along with pressure in the system. When voltage is applied, the other versions and the refrigerant circuit pressure sensor exchange information with the Data bus (for example, via the "LIN-Bus") with the corresponding control module. Refer to «Description and Operation»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .
4. The high pressure sensor is installed for Audi A3 2005 > and Audi Q3, and provides measured values as square-wave signals to the corresponding module (such as to the A/C control module -J301- or the Climatronic control module -J255-). Refer to the appropriate SYSTEM WIRING DIAGRAMS information.
5. The refrigerant circuit pressure sensor is installed for example, for Audi A3 2013> and exchanges information via the Data bus with the corresponding control module (for Audi A3 for example with the A/C control module or the Climatronic control module -J255-. Refer to the appropriate SYSTEM WIRING DIAGRAMS information.
6. The A/C pressure/temperature sensor, the refrigerant circuit pressure sensor and the high pressure sensor are available in different versions. Currently the sensor's only exterior difference is the part number. Therefore, make sure that the part numbers are correctly allocated when replacing them. Explanation: These sensors produce different signals that can only be identified by the corresponding control modules. Refer to the Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" for the A/C system), «Diagnosis and Testing»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .
7. The refrigerant circuit pressure sensor transfers only the measured values for the pressure within the refrigerant circuit for the closed control module. The A/C pressure/temperature sensor transfers the measured values for the pressure in the refrigerant circuit and the measured temperatures to the closed control module. Also if for a vehicle, only the pressure signal is interpreted, no A/C pressure/temperature sensor -G395- can or will be installed in a vehicle in where there is a refrigerant circuit pressure sensor -G805-.
8. The downstream control modules (coolant fan control, engine control module (ECM), Front A/C display control head -E87- or Climatronic control module -J255-, etc.) use this signal to calculate pressure in the refrigerant circuit and accordingly to activate the coolant fans and the motor, the A/C Clutch -N25-, or to change activation of the A/C compressor regulator valve -N280-. Refer to Vehicle Diagnostic Tester (function "OBD" or "Guided Fault Finding" for the A/C system). Refer to «Diagnosis and Testing»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#air-conditioning-avant) .

Scheme 303

The Refrigerant Temperature Sensor (with temperature-dependent resistance) is installed, for example, in high pressure line in vicinity of the compressor.

In the refrigerant circuit, there is a direct relationship between temperature and pressure, if there should be too little refrigerant in the refrigerant circuit, the temperature in the refrigerant circuit rises more strongly than intended for this pressure when A/C system is operating.

Note. Installed, for example, on the Audi Q7 with certain engines. Refer to Removal and Installation (vehicle-specific repair information) and refer to the appropriate SYSTEM WIRING DIAGRAMS information. The Climatronic control module -J255- evaluates pressure and temperature in the refrigerant circuit and switches off the compressor in the event the temperature increases above the value stored for this pressure. Refer to Description and Operation (vehicle-specific repair information) and Vehicle Diagnostic Tester.

RADIATOR FAN CONTROL MODULE -J293

This control module switches on and off the A/C clutch and therefore the A/C compressor. It turns on the radiator fan and calculates the refrigerant circuit pressure in vehicles with a High pressure sensor -G65-. Refer to the appropriate SYSTEM WIRING DIAGRAMS information and Description and Operation (vehicle-specific repair information).

Scheme 304

A/C SYSTEM, OPERATING AFTER CHARGING

Note. If the mechanically driven A/C compressor has been removed, rotate it about 10 times by hand prior to initial start-up (when or after installing, for example prior to installing the ribbed belt) to prevent damage caused by liquid impact when first switched on (any oil in compressor cylinder is forced out on rotation). If the mechanically driven A/C compressor has been removed, prior to initial start-up, activate it via the "basic setting, compressor cut-in" function for the Guided Fault Finding after filling the A/C compressor. Refer to the Vehicle Diagnostic Tester in the "Guided Fault Finding" Function for A/C System and Battery Controls. This prevents the A/C compressor from becoming damaged, for example, by liquid impact when it is first switched on (any oil in the A/C compression chamber is forced out). The vehicle engine drives the mechanically driven A/C compressor via a belt or shaft. The electric A/C compressor is driven by a electric motor attached directly on the A/C compressor (for example, for vehicles with hybrid drive).

Operating an A/C system with an mechanically driven A/C compressor

Start engine with compressor switched off (version with A/C clutch).

Scheme 305

Set compressor to minimum output, for example, "Econ" or A/C off mode (version with no A/C clutch with regulating valve).

Wait until idle speed has stabilized.

Switch on compressor and operate system for at least 2 minutes at idling speed.

If necessary, check pressures in refrigerant circuit using A/C service station.

Turn engine off.

Screw out handwheel on quick-release coupling adapter.

Disconnect charging hoses from refrigerant circuit.

Install the caps.

Operating an A/C system with an electrical driven A/C compressor

Operate the A/C using "basic setting, compressor cut-in" in Guide Fault Finding using the Vehicle Diagnostic Tester A/C System and Battery Regulation.

After the basic setting and If necessary, check pressures in refrigerant circuit using A/C service station.

Screw out handwheel on quick-release coupling adapter.

Disconnect charging hoses from refrigerant circuit.

Install the caps.

USING SERVICE STATION

Vehicles with a high voltage system (hybrid vehicles)

Read and follow all of the supplemental warnings for all work performed on vehicles with the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work in the vicinity of high voltage components, perform a visual inspection of the high voltage components and cables for damages. Refer to PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES and follow the warnings when working on the high voltage system. Refer to HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

If it is necessary to perform work on the high voltage components, disable the high voltage system. Refer to Disable the high voltage system below. and read and follow the high voltage electrical system general warnings in HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES .

Note. Working on the refrigerant circuit with the A/C service station usually requires, although not necessary, the high voltage system to be disabled.

Disable the high voltage system

Note. Disable the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - Disable the high voltage system (Rep.Gr. 93)

Restart the high voltage system

Note. Restart the high voltage system: Connect the vehicle diagnosis tester Select the Guided Fault Finding mode Using the GO TO button, select the following menu commands Functions/Component selection Body Electrical system OBD-capable system 8C - Hybrid battery management -J840 8C - Hybrid battery management, functions 51 - High voltage restart (Rep.Gr. 93)

Charge the vehicle battery using the VAS 5903 in the battery support mode to minimize the number of automatic starts during the test- and measuring procedures while the ready mode is active. Refer to General Information

Move the selector level into position "P", activate the parking brake and arrange the necessary tools for testing and measuring procedures that require the ready mode to be active or that require the ignition to be on, so that they cannot come into contact with the turning components in the engine and so that they are not in the vicinity of the turning components of a running engine.

Note. Also move the selector lever into position "P" and activate the parking brake for testing and measuring procedures which require the ignition to be on, but do not require the ready mode to be active. The ready mode is displayed in the instrument cluster control module -J285- above the "powermeter". Refer to the Owners Manual. Activate and deactivate the ready mode. Refer to the Owners Manual (consult the display in the instrument cluster control module -J285-).

Vehicles with Start/Stop System

All vehicles

Note. The chemical materials (stop leak additive) for sealing leaks in the refrigerant circuit offered on the market are not approved by Audi AG. There are no permanent-, validity or material compatibility tests. Therefore damage or malfunctions in the A/C system or the A/C Service Station cannot be excluded. The stop leak additives offered on the open market have different physical and chemical properties, which can impair the function of the A/C system and the A/C Service Station and can even shut down the system completely. Audi does not approve the use of chemicals to seal leaks in the refrigerant circuit (leak stop additives). Chemical materials to seal leaks in the refrigerant circuit react with air or the moisture in the air and form deposits in the refrigerant circuit and the A/C service station that lead to malfunctions in the valves and other components that come into contact with such chemicals. These deposits cannot be removed completely from the components, even by flushing. It is not possible to recognize chemical substances to seal leaks in the refrigerant circuit (leak stop additive) and the label that is supposed to come with them is usually not there. Therefore be careful when working with if you do not know its service history. Accessories offer containers used to separate out these chemicals (used to seal leaks in the refrigerant circuit). Since Audi does not know composition and the physical and chemical properties of these materials, it is not possible to make a statement about their effectiveness and the deposition rate of these filters. The Filter for sealants VAS 6592 offers a certain protection for the A/C service station. This filter is incorporated between the A/C service station and the Service connection on the low pressure side of the refrigerant circuit in a vehicle (the A/C service station may not be connection to the service connection of the high pressure side of the refrigerant circuit for draining, evacuating and measuring). This filter separate certain materials that were added to seal leaks in the refrigerant circuit. It prevents these materials from getting into the refrigerant and refrigerant oil in the A/C service station unchecked and doing damage. For the protection to work, it is necessary that the filter be changed in regular intervals and exactly according to the manufacturer specifications (described in the instructions provided). Audi does not support using chemical materials (stop leak additives) for sealing leaks in the refrigerant circuit. There are many different formulas of these chemicals (stop leak additives), that are offered as "sealant for refrigerant circuits" and it is not possible to make a statement about the effectiveness of the VAS 6592.

If the refrigerant circuit gets filed with a chemical material (stop leak additive) to seal any leaks (or if there is a suspicion of this) and if it then necessary to perform a repair to the refrigerant circuit, then it is necessary to inform the customer of the following

1. It is not possible to evacuate the refrigerant from the A/C system due to the stop leak additive that has been added to the system because it will damage the A/C Service Station. It will necessary to hire an outside company the can evacuate the contaminated refrigerant with a suitable device and then dispose of it (for example, a local waste management company that specializes in disposing of refrigerant).
2. It will be necessary to replace any refrigerant circuit components that have come in contact wit the stop leak additive in order to repair the A/C system properly. Certain refrigerant circuit components may already be damaged by the stop leak additive (for example, the A/C compressor regulator valve -N280-) or will get damaged if they are used over again and will fail after a short amount of time. In addition to this, if there is any sediment from the stop leak additive still in the circuit, it could come loose at a later point and cause the A/C system to fail again (currently it is not possible to clean these components with any workshop tools).

Working on the A/C system refrigerant circuit

1. Service station, important usage information, refer to «USING SERVICE STATION => Service Station, Important Usage Information»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__using-service-station) .
2. Servicing station, connecting for measuring and testing, refer to «CONNECTING FOR MEASURING AND TESTING, ONE SERVICE CONNECTION»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__connecting-for-measuring-and-testing-one) .
3. Discharge refrigerant circuit using service station, refer to «DRAINING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__draining-refrigerant-circuit) .
4. Discharging refrigerant circuit using service station, refer to «EVACUATING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__evacuating-refrigerant-circuit) .
5. Refrigerant circuit, charging with service station, refer to «CHARGING REFRIGERANT CIRCUIT»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__charging-refrigerant-circuit) .
6. A/C system, operating after charging, refer to «A/C SYSTEM, OPERATING AFTER CHARGING»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__ac-system-operating-after-charging) .
7. Transferring refrigerant to reservoir (charging cylinder or reservoir bottle) of service station, refer to «TRANSFERRING REFRIGERANT TO RESERVOIR (CHARGING CYLINDER OR RESERVOIR BOTTLE) OF SERVICE STATION»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__transferring-refrigerant-to-reservoir-charging-cylinder) .
8. Service station, draining, refer to «DRAINING SERVICE STATION»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant__draining-service-station) .

Service Station, Important Usage Information

Observe the following with regard to service station operation (for example, V.A.G 1885).

The filters and dryers installed must be replaced at the latest on completion of the service life specified in the relevant operating instructions.

If a service station is also used for flushing the refrigerant circuit, dryer and filter must be replaced in shorter intervals. Refer to REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN .

Exclusive use is to be made of refrigerant oils which have been approved for the vehicle-specific refrigerant circuit (if necessary, fill refrigerant oil directly into refrigerant circuit).

Extracted refrigerant is not to be reused if there is any doubt about the composition of the refrigerant extracted, even after cleaning in the service station.

The service station is to be drained in all these cases, refer to A/C SERVICE STATION , the system cleaned if necessary and the filters, dryers and refrigerant oil replaced.

For example, within Germany, contaminated refrigerant can be returned to the supplier in recycling containers for recycling or for environmentally safe disposal. Other or additional regulations may apply in other countries.

Commercially available service stations can be classified in 2 groups

1. A. Service stations which clean extracted refrigerant for use (so-called extraction and recycling stations), for example, V.A.G 1885 .
2. B. Service stations which transfer extracted refrigerant to recycling containers (for large-scale recycling). These are referred to as extraction systems.

CHARGING REFRIGERANT CIRCUIT

Note. The entire refrigerant charge can be added to either on the high or low pressure side. Refer to REFRIGERANT OIL CAPACITIES .

1. The work procedure is always to be performed as described in the operating instructions for the A/C service station.
2. Before pouring in refrigerant, correct the quantity of refrigerant oil, refer to «REFRIGERANT OIL CAPACITIES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__refrigerant-oil-capacities) .
3. Make sure the A/C service station is standing at the same level as the vehicle (maximum difference: 50 cm) when charging the refrigerant circuit. If a difference in height is large enough, a difference between the amount of refrigerant displayed on the service station and amount actually filled in the circuit will result (depending on the version of the A/C service station). The ability of the A/C Service Station to perform an exact filling can change.

Switch off the ignition.

Discharging refrigerant circuit using service station. Refer to EVACUATING REFRIGERANT CIRCUIT .

Screw out handwheel at quick-release coupling adapter (to close it).

Allow refrigerant to flow into charging hose.

Check charging cylinder

Screw in handwheel at quick-release coupling adapter (to open it) and charge with the specified quantity of refrigerant.

Switch off service station.

CONNECTING FOR MEASURING AND TESTING, TWO SERVICE CONNECTIONS

Connecting on vehicles with connections on low- and high pressure side of refrigerant circuit

Switch off the ignition.

Connect service station to power supply.

Connect quick-release coupling adapter to charging hoses of service station (handwheels not screwed in/hand shut-off valve not open).

Switch on service station and evacuate charging hoses (only necessary if there is air in charging hoses).

Switch off service station.

Remove caps from service connections (with valve).

Connect service station via service connections with quick-release coupling adapters to vehicle refrigerant circuit.

Screw in handwheel of quick-release coupling adapters only until valves are definitely open at refrigerant circuit connection (observe pressure gauge, do not strain valves).

Perform planned tests and measurements.

CONNECTING FOR MEASURING AND TESTING, ONE SERVICE CONNECTION

Special tools and workshop equipment required

1. Valve Adapters V.A.G 1785/9
2. V.A.G 1785/10 or Air Conditioning Adapter Set V.A.G 1786

1. Work procedure may vary depending on the type of tools selected (the tool-specific operating instructions should therefore be followed).

Note. The work procedure is always to be performed as described in the operating instructions for the A/C service station.

The charging hoses are to be connected as follows to prevent the entry of air or moisture into the refrigerant circuit

Switch off the ignition.

Connect service station to power supply.

Remove the caps from the service connections or connections with valve (refer to vehicle-specific refrigerant circuit). Refer to Removal and Installation (vehicle-specific repair information).

Evacuate charging hoses if necessary.

Connect quick-release coupling to service connection of refrigerant circuit.

Only tighten the handwheel in the quick-release coupling just enough so the service connection is open. Watch the pressure gauge and do not place too much pressure on the valve.

Start the engine and perform the planned tests and measurements.

Compare values determined to specified measured values. Refer to PRESSURES, CHECKING .

Before disconnecting quick-release coupling, close it by screwing out handwheel.

Vehicles with only one service connection

Note. Screw V.A.G 1785/9, V.A.G 1785/10 or V.A.G 1786 to refrigerant circuit connections with valve and bleed charging hoses during connection to adapters (faintly audible escape of refrigerant gas is permitted).

The charging hose must be installed with a valve opener for opening valve in valve adapter.

CONNECTING FOR MEASURING AND TESTING, NO SERVICE CONNECTION

On the following vehicles, no service connection is provided for the service station on the low-pressure side of the refrigerant circuit; adapters must be used to connect the service station to the refrigerant circuit on these vehicles

1. Audi 80, Audi Cabrio, Audi Coupe
2. Audi A4 up to 07.96
3. Audi 100/ Audi A6 up to 03.97
4. Audi A8 up to 11.97

Note. On vehicles with no or inaccessible connection at compressor, remove A/C Refrigerant Low Pressure Switch -F73- (bridge terminals in connector to A/C Refrigerant Low Pressure Switch -F73-) and screw adapter to this connection. Refer to Removal and Installation (vehicle-specific repair information).

Note. The tools listed below are commercially available or can be obtained from local distributor or importer. Should it be necessary to measure pressures at switch connections on high-pressure side, use Adapter set for refrigerant circuit V.A.G 1785/9 and proceed in the same manner.

1. Service station, connecting with Air conditioning adapter set V.A.G 1786 to refrigerant circuit, refer to «CONNECTING WITH Air Conditioning Adapter Set V.A.G 1786»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant)
2. Service station, connecting with adapter V.A.G 1785/10 to refrigerant circuit, refer to «CONNECTING WITH Adapter Set VAG1785/10»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-general-information-avant) .

Servicing Station, Connecting for Measuring and Testing

Switch off the ignition.

Connect service station to power supply.

Assemble adapter set and screw to connection on low-pressure side.

Connect quick-release coupling adapter to charging hoses of service station (handwheels not screwed in/hand shut-off valve not open).

Switch on service station and evacuate charging hoses (only necessary if there is air in charging hoses).

Switch off service station.

Remove the cap from service connection/connection with valve (or remove low-pressure switch and bridge respective electrical connections).

Connect service station via service connections with quick-release coupling adapters to vehicle refrigerant circuit.

Install the handwheel on the quick-release coupling adapters only until valve is definitely open at refrigerant circuit connection (observe pressure gauge, do not strain valve).

Perform planned tests and measurements.

Scheme 306

A - Connection with valve (small valve insert) on low-pressure side of refrigerant circuit

B - Adapter with union nut V.A.G 1786/1

C - Commercially available charging hose (short version with 5/8" thread on each end).

D - Adapter with service connection V.A.G 1786/2 (for connection of quick-release coupling of service station -E-).

Note. Assemble adapter and charging hose as shown and connect to connection with valve -A- first. The Adapter with union nut V.A.G 1786/1 is only to be used at connections with small valve insert (standard for connection with valve for A/C Refrigerant Low Pressure Switch F73 and gradually introduced as of 10.94 also at compressor). Instead of Adapter with union nut V.A.G 1786/1, also Adapter V.A.G 1785/10 can be used (remove valve from Adapter V.A.G 1785/10 or install valve opener in charging hose).

Scheme 307

Remove the cap from the connection with valve -A- (at A/C compressor).

Attach O-ring -B- to connection (8.9 mm; 1.8 mm).

Screw adapter V.A.G 1785/10 -C- to connection -B-.

Install valve opener -D- with appropriate seal in charging hose connection.

Note. The type of valve opener -D- and seals required depends on charging hose used (specific to manufacturer). The quick-release coupling adapter is not required for connection on the low-pressure side of Audi vehicles. Screw charging hose -E- (to service station) to Adapter V.A.G 1785/10.

Note. To minimize the amount of air and moisture penetrating into the charging hoses and thus into the refrigerant circuit, the charging hoses should be connected together as illustrated.

A - Charging hose to service station

B - Hand shut-off valve

C - Charging hose (short version) with valve opener for connection to adapter -D

D - Adapter V.A.G 1785/10

E - Charging hose (short version) with quick-release coupling adapter (for vehicles with quick-release coupling adapter on low-pressure side).

Perform planned tests and measurements.

DRAINING REFRIGERANT CIRCUIT

1. Work procedure may vary depending on the type of tools selected (the tool-specific operating instructions should therefore be followed).
2. The refrigerant circuit is to be discharged if parts of the refrigerant circuit are to be removed, if there is any doubt about the quantity of refrigerant in the circuit or if safety precautions so require.
3. All the necessary usage information for working with the refrigerant service station can be found in the service station operating instructions.

Draining

Switch off the ignition.

Connect service station in line with operating instructions to vehicle service connections (refer to vehicle-specific refrigerant circuit) and start up service station. Refer to General Information (vehicle-specific repair information).

Discharge the refrigerant circuit using the A/C service station according to the corresponding operating instructions.

Note. There is a possibility of refrigerant oil being extracted from the refrigerant circuit together with the refrigerant. To ensure compressor lubrication, the refrigerant oil in the circuit must be topped up with fresh oil. Refer to REFRIGERANT OIL CAPACITIES . On vehicles fitted with a compressor with no A/C clutch (with A/C compressor regulator valve -N280-) the engine should not be run for longer than absolutely necessary with the refrigerant circuit empty (A/C compressor always in operation as well). On vehicles with a compressor with no A/C clutch, the engine is only to be started following complete assembly of the refrigerant circuit (avoid high engine speeds). Depending on the A/C compressor version, there may be a valve installed on the high pressure side of the A/C compressor, which prevents the liquid refrigerant from flowing back into the compressor once the A/C is turned off. If an A/C compressor with this valve is installed in a vehicle with a refrigerant circuit having an expansion valve, then it may take some time until the pressure in the high pressure side decreases (the expansion is cold and the pressure in the low pressure side quickly increases after it is turned off, the expansion valve closes and the refrigerant flows slowly into the low pressure side). If the A/C compressor is switched on (or the refrigerant circuit is evacuated on the low pressure side) the pressure on the low pressure side goes down, the expansion valve open and the refrigerant can flow of the low pressure side.

Should be performed on the vehicle after the discharge work, for which the A/C Service Station is not required.

Disconnect the A/C Service Station from the refrigerant circuit and turn it off.

After the refrigerant circuit is evacuated and refilled, refer to CHARGING REFRIGERANT CIRCUIT .

DRAINING SERVICE STATION

Note. If it is necessary to drain the service station (for example, due to extraction of contaminated refrigerant), all filters and dryers must always be replaced (do not remove filter and dryer from the air-tight packaging until immediately before installation to minimize moisture absorption). Refrigerant containers filled with contaminated used refrigerant are referred to as "Recycling containers". Always evacuate recycling containers prior to initial filling with refrigerant (if there is air in a refrigerant container it is not to be filled with refrigerant). Different types of refrigerant are not to be mixed (refrigerant mixtures cannot be recycled and are to be disposed of). If there is any doubt about the composition of the contents of the container, the refrigerant recycling company is to be informed accordingly.

EVACUATING REFRIGERANT CIRCUIT

1. The work procedure is always to be performed as described in the operating instructions for the A/C service station.
2. Quantity of refrigerant oil in circuit checked and if necessary corrected. Refer to «REFRIGERANT OIL CAPACITIES»(/audi/a4/b8-2007-2012/remont/automatic-hvac-system/#general-technical-data-refrigerant-r134a-servicing-avant__refrigerant-oil-capacities) .
3. Check quantity of refrigerant in the service station.

The refrigerant circuit must be evacuated before it is filled with refrigerant (vacuum). Moisture is also extracted from the circuit.

Leaks may be found when evacuating the refrigerant circuit.

Evacuating

Switch off the ignition.

Connect service station to power supply.

Connect charging hose of service station to vehicles refrigerant circuit with quick-release coupling adapter (refer to vehicle-specific refrigerant circuit). Refer to General Information (vehicle-specific repair information).

Only tighten the handwheel on the quick-release coupling adapter just enough so the valves in the service connections are securely open. Do not put too much pressure on the valve.

Note. If pressure is to be measured after charging system on vehicles with a service connection on one side of the refrigerant circuit only, use valve adapter and charging hose with valve opener. Refer to CONNECTING FOR MEASURING AND TESTING, ONE SERVICE CONNECTION .

Switch on service station and evacuate refrigerant circuit for at least 30 minutes. The pressure reading must indicate an absolute pressure of less than 10 mbar (corresponding to 990 mbar vacuum).

Note. At this pressure, both green LEDs light for example on service station V.A.G 1885 .

Switch off service station and allow to stand for at least 1 hour.

1. If the vacuum display (LED chain) does not change, the system is free of leaks and can be charged.

Note. A current vacuum reading (LED) is only obtained using V.A.G 1885, for example after pressing the "Evacuate" button again. If with this service station the upper (green) LEDs do not light immediately after switching on, either the refrigerant circuit is leaking or there is still residual moisture/refrigerant in the circuit.

If the vacuum is not maintained or cannot generate a sufficient vacuum, perform the following

1. Did the pressure in refrigerant circuit increase slowly after evacuating, for example, through evaporation.

If it is possible that the refrigerant circuit may have leaks, evacuate and check the vacuum display again over several hours Only when the vacuum is maintained can the refrigerant circuit be charged.

If the refrigerant circuit is sealed, it can be filled.

1. If there is a leak that allowed enough air to enter during evacuation that the A/C service station cannot generate a sufficient vacuum or that the vacuum is lost immediately after switching the A/C service station off

Determine the location of the leak in the refrigerant circuit as follows

Note. A large leak can be identified if a maximum of pressure of 15 bar can be generated in the refrigerant circuit using clean, dry compressed air or nitrogen. Refer to REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN . If the leak is large enough, the sound of escaping air or gas can be heard at the location of the leak. Add the compressed air or nitrogen to the closed refrigerant circuit through the service connection after fitting it with a quick-release connector adapter. The quick-release coupling adapter for service connections can be connected to the air compressor using a modified filler hose -A- (for example, with 5/8" 18 UNF threads, different from the threads on the quick-release coupling adapter) and a suitable adapter -B-. Refer to IMPROVISED TOOLS . This keeps humidity, oil and dirt coming out of the workshop compressed air system from getting into the A/C refrigerant circuit. Also use a combination fine-gauge filter for compressed air systems such as those that are standard in paint shops. Install it between the compressed air system and the filler hose -A-. A compressed gas cylinder filled with nitrogen -3- can be connected to the closed refrigerant circuit using a pressure gauge battery with a pressure reducer for nitrogen (maximum reduction pressure: 15 bar) -1- and a filler hose -2- (for example, with 5/8" 18 UNF threads) connected to the service connection. A quick-release coupling adapter must also be connected to the service connection. Refer to IMPROVISED TOOLS .

Slowly increase the pressure in the refrigerant circuit to a maximum of 15 bar.

Find the location of the leak by listening for the sound of venting gas.

Repair the leak.

Evacuate and again observe the vacuum display over a period of hours. Only when the vacuum is maintained can the refrigerant circuit be charged.

1. If there is a leak that is small enough that no air or very little air vents through it and the A/C service station can generate a sufficient vacuum: The vacuum indicator does not increase after switching the A/C system service station or only increases slowly, indicating that air is only entering through a small leak.

Add 100 grams of refrigerant to the circuit, find the location of the leak using an electronic leak detector and repair it. Refer to REFRIGERANT CIRCUIT, TRACING LEAKS USING ELECTRONIC LEAK DETECTOR V.A.G 1796 . Or add UV contrast dye to the refrigerant and find the location of the leak with the leak detection system VAS 6201 and repair it. Refer to LEAK DETECTION ON REFRIGERANT CIRCUIT USING LEAK DETECTION SYSTEM VAS 6201 .

Empty the refrigerant circuit, if necessary. Refer to DRAINING REFRIGERANT CIRCUIT .

Evacuate and check the vacuum display again over several hours. Only when the vacuum is maintained can the refrigerant circuit be charged.

TRANSFERRING REFRIGERANT TO RESERVOIR (CHARGING CYLINDER OR RESERVOIR BOTTLE) OF SERVICE STATION

1. The work procedure is always to be performed as described in the operating instructions for the A/C service station.
2. A certain quantity of refrigerant is specified as charge for each air conditioning system. To ensure that neither too much nor too little refrigerant is added (either would reduce the cooling output), the charging cylinder has a scale indicating the weight.
3. The volume of a refrigerant changes as a function of pressure. The scale must therefore be set according to the pressure in the charging cylinder.

Note. Do not completely drain the reservoir (charging cylinder or bottle) as the liquid column boundary layer cannot be traced in the tube during filling (outside visible range).

CHARGING REFRIGERANT

Note. When charging the high-pressure side of refrigerant circuits, always use maximum amount of refrigerant (some of the refrigerant remains in the charging hoses). The specified capacities for refrigerant R134a apply if no other different specifications given for the S and RS. Make sure theA/C service station is standing at the same level as the vehicle (maximum difference: 50 cm) when charging the refrigerant circuit. If a difference in height is large enough, a difference between the amount of refrigerant displayed on the service station and amount actually filled in the circuit will result (depending on the version of the A/C service station). The ability of the A/C Service Station to perform an exact filling can change. For compressor allocation (Zexel / Valeo, Sanden or Denso / Nippondenso) refer to Removal and Installation (vehicle-specific repair information). Beginning the production year 2006, the name of the Zexel A/C compressor was changed from Zexel to Valeo.

See also:
• REFRIGERANT OILS
• General Information
• SPECIAL TOOLS
• REFRIGERANT CIRCUIT, DETERMINING LEAKS
• REFRIGERANT R134A CAPACITIES
• LEAKING OR DAMAGED COMPONENTS EXCEPT A/C COMPRESSOR, ACCUMULATOR OR RECEIVER - CIRCUIT EMPTY OF REFRIGERANT
• COMPRESSOR, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT
• COMPRESSOR, REPLACING DUE TO LEAKAGE OR INTERNAL DAMAGE
• RECEIVER OR ACCUMULATOR AND RESTRICTOR, REPLACING AFTER CLEANING REFRIGERANT CIRCUIT
• RECEIVER OR ACCUMULATOR, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT
• DRYER CARTRIDGE AND DRYER BAG, REPLACING WITHOUT FLUSHING REFRIGERANT CIRCUIT
• Removal and Installation
• REFRIGERANT OIL CAPACITIES
• PRESSURE GAUGE, TESTS AND MEASUREMENTS
• General Information
• PRESSURES, CHECKING
• IMPROVISED TOOLS
• REFRIGERANT CIRCUIT, TRACING LEAKS USING ELECTRONIC LEAK DETECTOR V.A.G 1796
• LEAK DETECTION ON REFRIGERANT CIRCUIT USING LEAK DETECTION SYSTEM VAS 6201
• HYBRID VEHICLE HIGH VOLTAGE SYSTEM PROCEDURES
• REFRIGERANT R134A CHARACTERISTICS
• LAWS AND REGULATIONS
• REFRIGERANT R134A VAPOR PRESSURE TABLE
• HANDLING PRESSURE VESSELS
• REFRIGERANT OIL CHARACTERISTICS
• REFRIGERANT CIRCUIT FLUSHING WITH REFRIGERANT R134A
• EXTRACTION SYSTEM GROUP CLASSIFICATIONS
• CHARGING SYSTEMS NOT REQUIRING A PERMIT
• PERFORMING A VISUAL INSPECTION OF DAMAGE TO HIGH VOLTAGE COMPONENTS AND CABLES
• REFRIGERANT CIRCUIT, CONVERTING R12 TO R134A AND SERVICING
• A/C SYSTEM AND REFRIGERANT R134A, SAFETY PRECAUTIONS
• REFRIGERANT CIRCUIT PRECAUTIONS
• COMFORT
• REFRIGERANT R134A
• REFRIGERANT CIRCUIT, CLEANING
• VEHICLES WITH A/C COMPRESSOR WITHOUT A/C CLUTCH, ONLY WITH A/C COMPRESSOR REGULATOR VALVE
• O-RING SEALS
• REFRIGERANT CIRCUIT FLUSHING WITH COMPRESSED AIR AND NITROGEN
• CONNECTIONS WITH PRIMARY SEALING VALVE (BALL VALVE)
• REFRIGERANT CIRCUIT WITH EXPANSION VALVE, PRESSURES AND TEMPERATURES
• REFRIGERANT CIRCUIT WITH RESTRICTOR AND RESERVOIR, PRESSURES AND TEMPERATURES
• EVACUATING REFRIGERANT CIRCUIT
• CHARGING REFRIGERANT CIRCUIT
• A/C SYSTEM, OPERATING AFTER CHARGING
• REFRIGERANT CIRCUIT, FLUSHING
• ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT
• DRAINING REFRIGERANT CIRCUIT
• FLUSHING CIRCUIT BLOCK DIAGRAMS
• ELECTRICALLY DRIVEN A/C COMPRESSOR, RINSING (REMOVE REFRIGERANT OIL)
• REFRIGERANT CIRCUIT COMPONENTS, HIGH AND LOW PRESSURE SIDES
• CONNECTIONS FOR QUICK-RELEASE COUPLING ON REFRIGERANT CIRCUIT
• REFRIGERANT CIRCUIT PRESSURES AND TEMPERATURES
• SERVICE AND RECYCLING UNITS
• REPAIRING A/C SYSTEM
• Refrigerant Circuit With Expansion Valve, Fluid Reservoir and Second Evaporator
• A/C COMPRESSOR, MECHANICALLY DRIVEN
• A/C COMPRESSOR, ELECTRICALLY DRIVEN
• CONDENSER
• EVAPORATOR
• RESERVOIR
• RESTRICTOR
• FLUID RESERVOIR
• EXPANSION VALVE
• REFRIGERANT PIPE WITH INNER HEAT EXCHANGER
• QUICK-RELEASE CONNECTIONS ON REFRIGERANT LINES
• REFRIGERANT CIRCUIT PIPES AND HOSES
• PRESSURE RELIEF VALVE
• USING SERVICE STATION => Service Station, Important Usage Information
• CONNECTING FOR MEASURING AND TESTING, ONE SERVICE CONNECTION
• TRANSFERRING REFRIGERANT TO RESERVOIR (CHARGING CYLINDER OR RESERVOIR BOTTLE) OF SERVICE STATION
• DRAINING SERVICE STATION