Air Conditioning: Diagnosis Audi A3 8P facelift

TEST REQUIREMENTS

1. Ambient temperature greater than 15 °C.
2. Clean radiator and condenser (clean if necessary).
3. The ribbed belt, which drives the A/C compressor, is OK and is tensioned correctly. The ribbed belt is actually driving the A/C compressor.
4. All air ducts, covers and seals OK and properly installed.
5. Air flow through dust and pollen filter not obstructed by dirt.
6. Air intake apparatus (in fresh air and recirculating air mode) is not impaired by soiling or components installed as retrofit.
7. Vehicle not exposed to sunlight.
8. Engine is warm.
9. The Climatronic control module was checked and erased and a basic setting was performed using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".
10. The Climatronic control module coding has been checked using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".
11. The Climatronic control module adaptation has been checked using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".

Adjustments on vehicle

Open all instrument panel vents.

Close hood.

Set operating mode "Auto" Auto on Climatronic control module.

Set temperature preselect for driver and front passenger side to Lo on Climatronic control module.

Functions with engine running

1. Fresh Air Blower -V2- runs at maximum speed.
2. The air conditioner goes in recirculating air mode (approximately 1 minute after starting the engine), the fresh air intake is closed and the recirculating air intake opens (fresh air blower extracts the air from passenger compartment below instrument panel / glove compartment).
3. The Coolant Fans -V7- run (activation and speed depends on pressure in refrigerant circuit and on the engine temperature).

Note. Depending on version of Climatronic control module, coolant fan is switched on immediately or only from a certain pressure in refrigerant circuit (from a pressure of 9 bar at this time). The actuation of the coolant fan is displayed in the vehicle electrical system control module measured values block using Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function. If one of these test requirements is not fulfilled, perform Guided Fault Finding using Vehicle Diagnosis, Testing and Information System VAS 5051.

CONTINUATION OF TEST: PRESSURE IN REFRIGERANT CIRCUIT INCREASES

Note. The pressure in the refrigerant circuit depends on several factors. However, in general, the pressure should not exceed 20 bar at an ambient temperature of 20 to 25 °C. Pressures up to 31 bar may occur due to extremely high performance under severe conditions (such as in southern countries with a hot climate, "stop and go" traffic and high humidity). At temperatures below 25° C, the pressure in the refrigerant circuit generally does not rise above 16 bar (the coolant fans run and cool the condensers down). The Climatronic control module calculates the refrigerant circuit pressure via the duty cycle. If the duty cycle is less than 10% (matches approximately 1.2 bar absolute pressure) or greater than 78% (matches approximately 32 bar absolute pressure) the Climatronic control module does not switch on the A/C compressor (the A/C compressor regulator valve is not controlled). The A/C compressor is only switched on again after duty cycle has become greater than 12% (corresponds to 1.8 bar absolute pressure) or less than 48% (corresponds to 16 bar absolute pressure). If the pressure in the refrigerant circuit or the engine coolant temperature is too high, the Climatronic control module regulates the A/C compressor performance (to avoid sudden compressor cut-off): As soon as the refrigerant circuit pressure goes above 30 bar (absolute pressure). The full A/C compressor output will be released once after the pressure is less than 27 bar or when the coolant temperature goes above 115 °C (the A/C compressor switches off completely at 118 °C). If the pressure in the refrigerant circuit was greater than 32 bar (duty cycle greater than 78%) the A/C compressor is switched on again by Climatronic control module, if pressure drops below 29 bar (duty cycle is less than 74%). Additional information regarding the pressure in the refrigerant circuit can be found in Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".

1. Ambient temperature greater than 15 °C
2. Clean radiator and condenser (clean if necessary).
3. The ribbed belt, which drives the A/C compressor, is OK and is tensioned correctly. The ribbed belt is actually driving the A/C compressor.
4. All air guides, covers and seal OK and properly installed.
5. Air flow through dust and pollen filter not obstructed by dirt.
6. Air intake apparatus (in fresh air and recirculating air mode) is not impaired by soiling or components installed as retrofit.
7. Vehicle not exposed to sunlight.
8. Engine is warm.
9. The A/C control module DTC memory was checked and erased and a basic setting was performed using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".

Adjustments on vehicle

1. Open all instrument panel vents.
2. Close hood.
3. Set the lowest possible temperature (temperature rotary switch turned all the way to cold) on A/C control module.
4. Switch on the A/C compressor using the AC button on A/C control module (indicator lamp in AC comes on)
5. Switch A/C system to recirculating air mode by pressing recirculating air mode button on A/C control module (indicator lamp in recirculating air button lights up).
6. Set the air flow direction to instrument panel vents via the air distribution rotary switch on A/C control module.
7. Set speed 4 on fresh air blower rotary switch.

Functions with engine running

1. Fresh Air Blower -V2- runs at maximum speed.
2. A/C system initiates recirculating air mode, the fresh air intake is closed and the recirculating air intake is opened (Fresh Air Blower extracts air from passenger compartment under instrument panel / glove compartment).
3. The Coolant Fans -V7- run (activation and speed depends on pressure in refrigerant circuit and on the engine temperature).

Note. Depending on version of A/C control module, coolant fan is switched on immediately or only from a certain pressure in refrigerant circuit (from a pressure of 9 bar at this time). The coolant fan activation is displayed in the measured values block using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding". If one of these test requirement is not met, check the DTC memory, perform an output diagnostics test and read the measured values block using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".

Note. The pressure in the refrigerant circuit depends on several factors. However, in general, the pressure should not exceed 20 bar at an ambient temperature of 20 to 25 °C. Pressures up to 31 bar may occur due to extremely high performance under severe conditions (such as in southern countries with a hot climate, stop and go traffic and high humidity). At temperatures below 25° C, the pressure in the refrigerant circuit generally does not rise above 16 bar (the coolant fans run and cool the condensers down). Depending on the measured value, the A/C control module controls the A/C compressor regulator valve and tells the engine control module, via the data bus to control the coolant fan. If the absolute pressure is less than 1.2 bar or greater than approximately 32 bar, then the A/C control module will not turn on the A/C compressor (the A/C compressor regulator valve is not controlled). The A/C compressor is switched on again only after the measured absolute pressure has become greater than 1.8 bar or less than 16 bar. To prevent the A/C compressor from suddenly switching off because there is too much pressure in the in the refrigerant circuit or because the coolant temperature is too high, the A/C control module controls its power as soon as the refrigerant circuit pressure goes above 30 bar (absolute pressure) or the coolant temperature reaches 115 °C. Full A/C compressor output is released again after the pressure goes below 27 bar. If the coolant temperature goes above 115 °C, the A/C compressor output will continue to be controlled by the A/C control module. At 118 °C it is completely switched off. If the refrigerant circuit pressure was greater than 32 bar, the A/C control module switches on the A/C compressor again only when the pressure has decreased below 29 bar. Additional information regarding the pressure in the refrigerant circuit can be found in Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".