HVAC Systems: Other Isuzu Axiom I

SERVICE PRECAUTION

HEATER

When the engine is warming up, the warmed engine coolant is sent into the heater core. The heater system supplies warm air into the passenger compartment to warm it up.

Outside air is circulated through the heater core of the heater unit and then into the passenger compartment. By controlling the mixture of outside air and heater core air, the most comfortable passenger compartment temperature can be selected and maintained.

The temperature of warm air sent to the passenger compartment is controlled by the temperature control knob. This knob acts to open and close the air mix door, thus controlling the amount of air passed through the heater core.

The air selector switch (Mode SW), with its different modes, also allows you to select and maintain the most comfortable passenger compartment temperature.

The air source select switch is used to select either "FRESH" for the introduction of the outside air, or "CIRC" for the circulation of the inside air. When the switch is set to "FRESH", the outside air is always taken into the passenger compartment. When setting the switch to "CIRC" position, the circulation of air is restricted only to the inside air with no introduction of the outside air and the air in the passenger compartment gets warm quickly. However, the switch is normally set to "FRESH" to prevent the windshield from clouding.

Scheme 84

AIR SOURCE SELECT SWITCH

Press this button to select either Fresh Air Intake or CIRC (inside air circulation). There is an indicator light inside the button. This light indicates that the CIRC mode is "ON".

Fresh Air Intake is the default setting for both DEFROST and FOOT/DEFROST.

FAN CONTROL SWITCH

This switch controls the blower motor speed to regulate the amount of air delivered to the defrost, foot, and ventilation ducts

1. L0
2. M1
3. M2
4. M3
5. HI

TEMPERATURE CONTROL SWITCH

When the temperature control switch is in the "18°C (65°F)" position, the air mix door closes to block the air flow to the heater core.

When the temperature control switch is in the "32°C (90°F)" position, the air mix door opens to allow air to pass through the heater core and heat the passenger compartment.

Selecting the desired temperature will control the air flow through the heater core, allowing control of the cabin temperature.

Scheme 85

EVAPORATION

The refrigerant is changed from a liquid to a gas inside the evaporator. The refrigerant mist that enters the evaporator vaporizes readily. The liquid refrigerant removes the required quantity of heat (latent heat of vaporization) from the air around the evaporator core cooling fins and rapidly vaporizes. Removing the heat cools the air, which is then radiated from the fins and lowers the temperature of the air inside the vehicle.

The refrigerant liquid sent from the expansion valve and the vaporized refrigerant gas are both present inside the evaporator as the liquid is converted to gas.

With this change from liquid to gas, the pressure inside the evaporator must be kept low enough for vaporization to occur at a lower temperature. Because of that, the vaporized refrigerant is sucked into the compressor.

COMPRESSION

The refrigerant is compressed by the compressor until it is easily liquefied at normal temperature.

The vaporized refrigerant in the evaporator is sucked into the compressor. This action maintains the refrigerant inside the evaporator at a low pressure so that it can easily vaporize, even at low temperatures close to 0°C (32° F).

Also, the refrigerant sucked into the compressor is compressed inside the cylinder to increase the pressure and temperature to values such that the refrigerant can easily liquefy at normal ambient temperatures.

CONDENSATION

The refrigerant inside the condenser is cooled by the outside air and changes from gas to liquid.

The high temperature, high pressure gas coming from the compressor is cooled and liquefied by the condenser with outside air and accumulated in the receiver/drier. The heat radiated to the outside air by the high temperature, high pressure gas in the compressor is called heat of condensation. This is the total quantity of heat (heat of vaporization) the refrigerant removes from the vehicle interior via the evaporator and the work (calculated as the quantity of heat) performed for compression.

EXPANSION

The expansion valve lowers the pressure of the refrigerant liquid so that it can easily vaporize.

The process of lowering the pressure to encourage vaporization before the liquefied refrigerant is sent to the evaporator is called expansion. In addition, the expansion valve controls the flow rate of the refrigerant liquid while decreasing the pressure.

That is, the quantity of refrigerant liquid vaporized inside the evaporator is determined by the quantity of heat which must be removed at a prescribed vaporization temperature. It is important that the quantity of refrigerant be controlled to exactly the right value.

COMPRESSOR

The compressor performs two main functions

1. It compresses low-pressure and low-temperature refrigerant vapor from the evaporator into high-pressure and high-temperature refrigerant vapor to the condenser.
2. It pumps refrigerant and refrigerant oil through the air conditioning system.

This vehicle is equipped with a five-vane rotary compressor.

The specified amount of the compressor oil is 150cc (5.0 fl. oz.).

The oil used in the HFC-134a system compressor differs from that used in R-12 systems.

Also, compressor oil to be used varies according to the compressor model. Be sure to avoid mixing two or more different types of oil.

If the wrong oil is used, lubrication will be poor and the compressor will seize or malfunction.

The magnetic clutch connector is a waterproof type.

MAGNETIC CLUTCH

The compressor is driven by the drive belt from the crank pulley of the engine. If the compressor is activated each time the engine is started, this causes too much load to the engine. The magnetic clutch transmits the power from the engine to the compressor and activates it when the air conditioning is ON. Also, it cuts off the power from the engine to the compressor when the air conditioning is OFF. Refer to Compressor Assembly in this section for magnetic clutch repair procedure.

Scheme 86

RECEIVER / DRIER

The receiver/drier performs four functions

1. As the quantity of refrigerant circulated varies depending on the refrigeration cycle conditions, sufficient refrigerant is stored for the refrigeration cycle to operate smoothly in accordance with fluctuations in the quantity circulated.
2. The liquefied refrigerant from the condenser is mixed with refrigerant gas containing air bubbles. If refrigerant containing air bubbles. If refrigerant containing air bubbles is sent to the expansion valve, the cooling capacity will decrease considerably. Therefore, the liquid and air bubbles are separated and only the liquid is sent to the expansion valve.
3. The receiver/drier utilizes a filter and drier to remove the dirt and water mixed in the cycling refrigerant.

A receiver/drier may fail due to a restriction inside the body of the unit. A restriction at the inlet to the receiver/drier will cause high pressure.

Outlet restrictions will be indicated by low pressure and little or no cooling. An excessively cold receiver/drier outlet may indicate a restriction.

The receiver/drier of this vehicle is made of aluminum with a smaller tank. It has a 300cc refrigerant capacity.

The refrigerant line connection has a bolt at the block joint, for easy servicing.

TRIPLE PRESSURE SWITCH (V6, A/T)

Triple pressure switch is installed on the upper part of the receiver/drier. This switch is constructed with a unitized

type of two switches. One of them is a low and high pressure switch (Dual pressure switch) to switch "ON" or "OFF" the magnetic clutch as a result of irregularly high-pressure or low pressure of the refrigerant. The other one is a medium pressure switch (Cycling switch) to switch "ON" or "OFF" the condenser fan sensing the condenser high side pressure.

TRIPLE PRESSURE SWITCH OPERATION

EXPANSION VALVE

This expansion valve is an external pressure type and it is installed at the evaporator intake port.

The expansion valve converts the high pressure liquid refrigerant sent from the receiver/drier to a low pressure liquid refrigerant by forcing it through a tiny port before sending it to the evaporator.

This type of expansion valve consists of a temperature sensor, diaphragm, ball valve, ball seat, spring adjustment screw, etc.

The temperature sensor contacts the evaporator outlet pipe, and converts changes in temperature to pressure. It then transmits these to the top chamber of the diaphragm.

The refrigerant pressure is transmitted to the diaphragm's bottom chamber through the external equalizing pressure tube.

The ball valve is connected to the diaphragm. The opening angle of the expansion valve is determined by the force acting on the diaphragm and the spring pressure.

The expansion valve regulates the flow rate of the refrigerant. Accordingly, when a malfunction occurs to this expansion valve, both discharge and suction pressure decreases, resulting in insufficient cooling capacity of the evaporator.

The calibration has been changed to match the characteristics of HFC-134a.

Scheme 87

EVAPORATOR

The evaporator cools and dehumidifies the air before the air enters the passenger compartment. High-pressure liquid refrigerant flows through the expansion valve into the low-pressure area of the evaporator. The heat in the air passing through the evaporator core is lost to the cooler surface of the core, thereby cooling the air.

As heat is lost between the air and the evaporator core surface, moisture in the vehicle condenses on the outside surface of the evaporator core and is drained off as water.

When the evaporator malfunctions, the trouble will show up as an inadequate supply of cool air. The cause is typically a partially plugged core due to dirt, or a malfunctioning blower motor.

The evaporator core with a laminate louver fin is a single-sided tank type where only one tank is provided under the core.

Scheme 88

DUCT SENSOR

The duct sensor is the sensor to detect temperature change of the side of evaporator blower coming by fresh recirculation of intake door or "on" "off" of compressor.

The temperature is converted to resistant rate.

And it works as thermostat to control to prevent freezing of evaporator.

This sensor is installed in the upper case of evaporator.

Scheme 89

REFRIGERANT LINE

Restriction in the refrigerant line will be indicated by

1. Suction line - A restricted suction line will cause low suction pressure at the compressor, low discharge pressure and little or no cooling.
2. Discharge line - A restriction in the discharge line generally will cause the discharge line to leak.
3. Liquid line - A liquid line restriction will be evidenced by low discharge and suction pressure and insufficient cooling.

Refrigerant flexible hoses that have a low permeability to refrigerant and moisture are used. These low permeability hoses have a special nylon layer on the inside.

Scheme 90

Scheme 91

Scheme 92

CHECKING THE REFRIGERANT SYSTEM WITH MANIFOLD GAUGE

Since Refrigerant -134a (HFC-134a) is used in the air conditioning system in this vehicle, be sure to use manifold gauges, charging hoses and other air conditioning service tools for HFC-134a when checking the refrigerant system.

CONDITIONS

1. Run the engine at idle
2. Air conditioning switch is "ON"
3. Run the blower motor at "HIGH" position (5 positions)
4. Temperature control set to "MAX COLD" (65°F)
5. Air source selector at "CIRC"
6. Open the engine hood
7. Close all the doors

NORMAL PRESSURE

1. At ambient temperature: approx. 25-30° C (77 - 86° F).
2. At low-pressure side: approx. 147.1-294.2 kPa (21.3 - 42.7 psi).
3. At high-pressure side: approx. 1372.9-1863.3 kPa (199.1 - 270.2 psi).

Refer to the table on the refrigerant pressure-temperature relationship.

Scheme 93

CONNECT THE MANIFOLD GAUGE

Low-pressure hose (LOW) - Suction side

High pressure hose (HI) - Discharge side

Scheme 94

Scheme 95

Scheme 96

A/C - Air Conditioning

1. Disconnect the connector and check for continuity between pressure switch side connector terminals (1) and (2).
2. Reconnect the connector to activate the A/C switch, and check to see if there is continuity between the chassis side connector terminals (3) and (4) and the fan operates.

Scheme 97

CONDENSER FAN

1. Disconnect the condenser fan connector.
2. Connect the battery positive terminal to the condenser fan side connector terminal No. C-16-1 and negative to the No. C-16-2.
3. Check that condenser fan is rotating correctly.

Scheme 98

REFRIGERANT LINE CONNECTIONS

Install new O-rings, if required. When disconnecting or connecting lines, use two wrenches to prevent the connecting portion from twisting or becoming damaged.

Scheme 99

When connecting the refrigerant line at a block joint, securely insert the projecting portion of the joint portion into the connecting hole on the unit side and secure with a bolt. Apply the specified compressor oil to the O-rings prior to connecting.

Scheme 100

O-rings (2) must be fitted in the groove (1) of refrigerant line.

Scheme 101

Insert the nut into the union.

First, tighten the nut by hand as much as possible, then tighten the nut to the specified torque.

Scheme 102

HIGH PRESSURE SIDE

1. Discharger section of compressor.
2. Inlet/outlet section of condenser.
3. Inlet/outlet section of receiver driver.
4. Inlet section of cooling unit.

LOW PRESSURE SIDE

1. Outlet section of cooling unit.
2. Intake section of compressor.

1. Pipe connection
2. Sealing section of shaft
3. Mating section or cylinder

CONDENSER

1. Pipe connection
2. Welds of condenser body

RECEIVER DRIVER

1. Pipe connection
2. Attaching section of pressure switch
3. Section around the sight glass

EVAPORATOR UNIT (COOLING UNIT)

1. Pipe connections
2. Connections of expansion valve
3. Brazed sections of evaporator

Note. The evaporator and expansion valve are contained in the case. Remove the drain hose or the resistor of the cooling unit and insert a leak detector when checking for any leak.

FLEXIBLE HOSE

1. Pipe connection
2. Caulking section of the hose
3. Hose (cracks, pinholes, flaws)

PIPE

1. Pipe connection
2. Pipe (cracks, flaws)

CHARGE VALVE

Note. The charge valve, which is used to connect the gauge manifold, is normally provided with a resin cap. When the valve inside gets deteriorated, refrigerant will leak out.

LEAK AT REFRIGERANT LINE CONNECTIONS

1. Check the torque on the refrigerant line fitting and, if too loose, tighten to the specified torque. Use two wrenches to prevent twisting and damage to the line. Do not over tighten.
2. Perform a leak test on the refrigerant line fitting.
3. If the leak is still present, discharge and recover the refrigerant from the system.
4. Replace the O-rings. O-rings cannot be reused. Always replace with new ones. Be sure to apply the specified compressor oil to the new O-rings.
5. Retighten the refrigerant line fitting to the specified torque. Use two wrenches to prevent twisting and damage to the line.
6. Evacuate, charge and retest the system.

LEAKS IN THE HOSE

If the compressor inlet or outlet hose is leaking, the entire hose must be replaced. The refrigerant hose must not be cut or spliced for repair.

1. Locate the leak.
2. Discharge and recover the refrigerant.
3. Remove the hose assembly. Cap the open connections at once.
4. Connect the new hose assembly. Use two wrenches to prevent twisting or damage to the hose fitting. Tighten the hose fitting to the specified torque.
5. Evacuate, charge and test the system.

COMPRESSOR LEAKS

If leaks are located around the compressor shaft seal or shell, replace or repair the compressor.

RECOVERY, RECYCLING, EVACUATION AND CHARGING OF HFC-134a

Air conditioning systems contain HFC-134a. This is a chemical mixture which requires special handling procedures to avoid personal injury.

1. Always wear safety goggles and protective gloves.
2. Always work in a well-ventilated area. Do not weld or steam clean on or near any vehicle installed air conditioning lines or components.
3. If HFC-134a should come in contact with any part of the body, flush the exposed area with cold water and immediately seek medical help.
4. If it is necessary to transport or carry any container of HFC-134a in a vehicle, do not carry it in the passenger compartment.
5. If it is necessary to fill a small HFC-134a container from a large one, never fill the container completely. Space should always be allowed above the liquid for expansion.
6. HFC-134a and R-12 should never be mixed as their compositions are not the same.
7. HFC-134a PAG oil tends to absorb moisture more quickly than R-12 mineral oil and, therefore, should be handled more carefully.
8. Keep HFC-134a containers stored below 40°C (104°F).

REFRIGERANT RECOVERY

The refrigerant must be discharged and recovered by using the J-39500 (ACR 4 :HFC-134a Refrigerant Recovery/Recycling/Recharging/System) or equivalent before removing or mounting air conditioning parts.

Scheme 103

1. Connect the high and low charging hoses of the ACR 4 (or equivalent) as shown below.
2. Recover the refrigerant by following the Manufacturer's Instructions.
3. When a part is removed, put a cap or a plug on the connecting portion so that dust, dirt or moisture cannot get into it.

REFRIGERANT RECYCLING

Recycle the refrigerant recovered by J-39500 (ACR 4 :HFC-134a Refrigerant Recovery / Recycling / Recharging / System) or equivalent.

For the details of the actual operation, follow the steps in the ACR 4 ACR(or equivalent) Manufacturer's Instructions.

Scheme 104

Note. Explained below is a method using a vacuum pump. Refer to the ACR 4 (or equivalent) manufacturers instructions when evacuating the system with a ACR 4 (or equivalent).

Air and moisture in the refrigerant will cause problems in the air conditioning system. Therefore, before charging the refrigerant, be sure to evacuate air and moisture thoroughly from the system.

1. Connect the gauge manifold. High-pressure valve (HI) - Discharge-side. Low-pressure valve (LOW) - Suction-side.
2. Discharge and recover the refrigerant.
3. Connect the center hose of the gauge manifold set to the vacuum pump inlet.
4. Operate the vacuum pump, open shutoff valve and then open both hand valves.
5. When the low-pressure gauge indicates approximately 750 mmHg (30 inHg), continue the evacuation for 5 minutes or more.
6. Close both hand valves and stop the vacuum pump.
7. Check to ensure that the pressure does not change after 10 minutes or more. If the pressure changes, check the system for leaks. If leaks occur, retighten the refrigerant line connections and repeat the evacuation steps.
8. If no leaks are found, again operate the vacuum pump for 20 minutes or more. After confirming that the gauge manifold pressure is at 750 mmHg (30 inHg), close both hand valves.
9. Close positive shutoff valve. Stop the vacuum pump and disconnect the center hose from the vacuum pump.

CHARGING THE REFRIGERANT SYSTEM

There are various methods of charging refrigerant into the air conditioning system.

These include using J-39500 (ACR 4 :HFC-134a Refrigerant Recovery/Recycling/Recharging/System) or equivalent and direct charging with a weight scale charging station.

ACR 4 (OR EQUIVALENT) METHOD

For the charging of refrigerant recovered by ACR 4 (or equivalent), follow the manufacturers instruction.

Scheme 105

Scheme 106

Scheme 107

1. Make sure the evacuation process is correctly completed.
2. Connect the center hose of the manifold gauge to the weight scale.
3. Connect the low pressure charging hose of the manifold gauge to the low pressure side service valve of the vehicle.
4. Connect the high pressure charging hose of the manifold gauge to the high pressure side service valve of the vehicle.
5. Place the refrigerant container (3) up right on a weight scale (4). Note the total weight before charging the refrigerant. Open the refrigerant container valve. Open the low side vale on the manifold gauge set. NOTE: Refer to the manufacturers instructions for a weight scale charging station.
6. Perform a system leak test: Charge the system with approximately 200 g (0.44 lbs) of HFC-134a. Make sure the high pressure valve of the manifold gauge is closed. Check to ensure that the degree of pressure does not change. Check for refrigerant leaks by using a HFC-134a leak detector. If a leak occurs, recover the refrigerant. Repair the leak and start all over again from the first step of evacuation.
7. If no leaks are found, continue charging refrigerant to the air conditioning system. Charge the refrigerant until the scale reading decreases by the amount of the charge specified. Specified amount: 700 g (1.54 lbs) If charging the system becomes difficult: Run the engine at idle and close all the vehicle doors. Turn A/C switch "ON". Set the fan switch to its highest position. Set the air source selector lever to "CIRC". Slowly open the low side valve on the manifold gauge set. WARNING: Be absolutely sure not to open the high pressure valve of the manifold gauge. Should the high pressure valve be opened, the high pressure refrigerant would flow backward, and this may cause the refrigerant container to burst.
8. When finished with the refrigerant charging, close the low pressure valve of the manifold gauge and container valve.
9. Check for refrigerant leaks.

CHECKING THE A/C SYSTEM

1. Run the engine and close all the vehicle doors.
2. Turn A/C switch "ON", set the fan switch to its highest position.
3. Set the air source switch to "CIRC", set the temperature switch to the full cool position.
4. Check the high and low pressure of the manifold gauge. Immediately after charging refrigerant, both high and low pressures might be slightly high, but they settle down to the pressure guidelines shown below: The ambient temperature should be between 25-30° C (77-86°F). The pressure guideline for the high-pressure side is approximately 1372.9-1863.3 kPa (199.1-270.2 psi). The pressure guideline for the low-pressure side is approximately 147.1-294.2 kPa (21.3-42.7 psi). If an abnormal pressure is found, refer to «CHECKING THE REFRIGERANT SYSTEM WITH MANIFOLD GAUGE»(ref-194286-S13557390942005092700000) .
5. Put your hand in front of the air outlet and move the temperature switch of the control panel to different positions. Check if the outlet temperature changes as selected by the control switch.

Scheme 108

Scheme 109

1. Disconnect the battery ground cable.
2. Discharge and recover refrigerant Refer to «REFRIGERANT RECOVERY»(ref-194286-S07511965142005092700000) .
3. Disconnect magnetic clutch harness connector.
4. Remove serpentine belt. Move serpentine belt tensioner to loose side using wrench then remove serpentine belt.
5. Disconnect refrigerant line connector. When removing the line connector, the connecting part should immediately be plugged or capped to prevent foreign matter from being mixed into the line.
6. Remove compressor.

DKV-14G TYPE COMPRESSOR

DKV-14G is equipped with five-vane rotary compressor.

These vanes are built into a rotor which is mounted on a shaft.

When the shaft rotates, the vanes built into the cylinder block assembly are operated by centrifugal force.

This changes the volume of the spare formed by the rotor and cylinder, resulting in the intake and compression of the refrigerant gas. The discharge valve and the valve stopper, which protects the discharge valve, are built into the cylinder block assembly. There is no suction valve but a shaft seal is installed between the shaft and head; a trigger valve, which applies back pressure to the vanes, is installed in the cylinder block and a refrigerant gas temperature sensor is installed in the front head.

The specified quantity of compressor oil is contained in the compressor to lubricate the various parts using the refrigerant gas discharge pressure.

Scheme 110

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Scheme 117

1. Using drive plate holder J-33939 (1) to prevent the drive plate from rotating, then remove the drive plate bolt.
2. Remove drive plate by using drive plate puller J-33944-A (2) and forcing screw J-33944-4 (1).
3. Remove shim (s).
4. Remove snap ring (1) by using snap ring pliers.
5. Remove pulley assembly by using pulley puller pilot J-38424 (2), pulley puller J-8433 (1) and pulley puller leg J-24092-2 (3).
6. Loosen screw and disconnect the field coil wire connector.
7. Loosen three screws and remove the field coil.

Scheme 118

DRIVE PLATE

If the frictional surface shows signs of damage due to excessive heat, the drive plate and pulley should be replaced.

COIL

Check coil for loose connector or cracked insulation.

Scheme 119

Scheme 120

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Scheme 122

Scheme 123

1. Install field coil. Align the located portion (1) of the field coil and compressor. Tighten the mounting screw to the specified torque. Torque: 5 N.m (44 lb in)
2. Connect the lead wire connector with the rubber hold and tighten the screw.
3. Install pulley assembly by using pulley installer J-33940-A (2) and drive handle J-8092 (1).
4. Install snap ring.
5. Install shim (s).
6. Install the drive plate to the compressor drive shaft together with the original shim(s) (1). Press the drive plate by hand.
7. Install drive plate bolt by using drive plate holder J-33939 (1) to prevent the drive plate from rotating. Tighten the drive plate bolt to the specified torque. Torque: 13 N.m (113 lb in) After tightening the drive plate bolt, check to be sure the pulley rotates smoothly. Check to be sure that the clutch clearance is between 0.3-0.6 mm (0.01-0.02 in.) If necessary, install adjusting shim(s). Adjusting shims are available in the following thickness: Thickness: 0.1 mm (0.0039 in.) Thickness: 0.3 mm (0.0118 in.) Thickness: 0.5 mm (0.0197 in.)

HANDLING OF OIL

1. The oil should be free from moisture, dust, metal powder, etc.
2. Do not mix with other oil.
3. The water content in the oil increases when exposed to the air. After use, seal oil from air immediately. (HFC-134a Vane Rotary Compressor Oil absorbs moisture very easily.)
4. The compressor oil must be stored in steel containers, not in plastic containers.

COMPRESSOR OIL CHECK

The oil used to lubricate the compressor is circulating with the refrigerant.

Whenever replacing any component of the system or a large amount of gas leakage occurs, add oil to maintain the original amount of oil.

Oil Capacity

Capacity total in system: 150cc (5.0 fl.oz)

Compressor (service parts) charging amount: 150 cc (5.0 fl.oz)

CHECKING AND ADJUSTING OIL QUANTITY FOR USED COMPRESSOR

1. Perform oil return operation. Refer to «OIL RETURN OPERATION»(ref-194286-S09525754172005092700000) .
2. Discharge and recover refrigerant and remove the compressor.
3. Drain the compressor oil and measure the extracted oil with a measuring cylinder.
4. If the amount of oil drained is much less than 90 cc (3.0 fl. oz.), some refrigerant may have leaked out. Conduct a leak tests on the connections of each system, and if necessary, repair or replace faulty parts.
5. Check the compressor oil contamination. (Refer to «CONTAMINATION OF COMPRESSOR OIL»(ref-194286-S30324619002005092700000) .)
6. Adjust the oil level following the next procedure below. OIL LEVEL ADJUSTMENT Collected Amount Charging Amount More Than 90 cm 3 (3.0 fl.oz) Same As Collected Amount Less Than 90 cm 3 (3.0 fl.oz) 90 cm 3 (3.0 fl.oz)
7. Install the compressor, then evacuate, charge and perform the oil return operation.
8. Check system operation.
9. WHEN IT IS IMPOSSIBLE TO PREFORM OIL RETURN OPERATION, THE COMPRESSOR OIL SHOULD BE CHECKED IN THE FOLLOWING ORDER: Discharge and recover refrigerant and remove the compressor. Drain the compressor oil and measure the extracted oil with a measuring cylinder. Check the oil for contamination. If more than 90 cc (3.0 fl. oz.) of oil is extracted from the compressor, supply the same amount of oil to the compressor to be installed. If the amount of oil extracted is less than 90 cc (3.0 fl. oz.), recheck the compressor oil in the following order. Supply 90 cc (3.0 fl. oz.) of oil to the compressor and install it onto the vehicle. Evacuate and recharge with the proper amount of refrigerant. Perform the oil return operation, refer to «OIL RETURN OPERATION»(ref-194286-S09525754172005092700000) . Remove the compressor and recheck the amount of oil. Adjust the compressor oil, if necessary. OIL LEVEL ADJUSTMENT Collected Amount Charging Amount More Than 90 cm 3 (3.0 fl.oz) Same As Collected Amount Less Than 90 cm 3 (3.0 fl.oz) 90 cm 3 (3.0 fl.oz)

CONTAMINATION OF COMPRESSOR OIL

Unlike engine oil, no cleaning agent is added to the compressor oil. Even if the compressor runs for a long period of time (approximately one season), the oil never becomes contaminated as long as there is nothing wrong with the compressor or its method of use.

CIRCUIT DIAGRAM

For automatic air conditioning system wiring diagram, see AIR CONDITIONING in SYSTEM WIRING DIAGRAMS.

AUTOMATIC AIR CONDITIONING CONTROL UNIT

The control unit features a prominent control and display panel that clearly shows air conditioner operational settings (delivered air volume, air outlet location, inside/outside air circulation, and set temperature). Desired temperature can be set in - 17°C (1°F) increments. The current setting appears on the digital display.

AUTOMATIC TEMPERATURE CONTROL

Vehicle interior temperature is maintained at the set level. It is unaffected by changes in vehicle speed, outside air temperature, and number of passengers.

MAXIMUM COOLING AND HEATING

Moving the switch to the 18°C (65°F) position provides maximum cooling. Moving the switch to the 32°C (90°F) position provides maximum heating.

AUTOMATIC AIR FLOW CONTROL

Air flow is automatically and precisely regulated in response to set temperature change and/or changes in heater unit mixing door aperture.

AUTOMATIC AIR OUTLET SELECTION

Appropriate air outlets (VENT, BE-LEVEL, FOOT, or DEF) are selected in response to changes in outlet temperatures. The mode switch permits manual selection of the desired air outlet.

AIR SOURCE (FRESH AIR INTAKE FROM OUTSIDE THE VEHICLE OR RECIRCULATION OF THE AIR INSIDE THE VEHICLE) SELECTION

Automatic switching between outside air (FRESH), recirculated inside air (RECIRC), or a combination of the two (MIX) occurs in response to changes in outlet temperatures. The intake switch permits manual selection of the air source (FRESH or RECIRC). Mixing of the two sources is not possible during manual operation. When the defrost mode switch (DEF) is pressed, the system automatically switches to outside air intake.

COOLER START-UP CONTROL

When the vehicle is parked in a hot area for an extended period of time, the evaporator becomes hot. When the cooler is turned on, hot air is blown into the vehicle until the evaporator cools down.

The cooler start-up control prevents blower operation until the evaporator is able to provide cool air.

HEATER START-UP CONTROL

When the vehicle is parked in a cold area for an extended period of time, the heater core becomes cold. When the heater is turned on, cold air is blown into the vehicle until the heater core heats up. The heater start-up control prevents blower operation to the air outlets until the heater core is able to provide warm air. Air is delivered through the defrost outlets.

SOLAR RADIATION OFFSET

The sun sensor uses a photodiode to precisely determine the amount of solar radiation affecting the vehicle. The cooler operates in response to this radiation to quickly correct the vehicle interior temperature.

SWITCH POSITION MEMORY

Current switch positions are stored in memory when the ignition switch is turned off. When the ignition switch is turned on again, the switches automatically return to the position they were in when the ignition switch was turned off. This simplifies the restarting procedure.

AUTOMATIC AIR CONDITIONER CONTROL UNIT

Equipped with the built-in micro-computer, this control unit operates on signals from sensors and input signals from switches to offer total control of the blower fan, and actuators used for the mode door, intake door and air mix door.

Its self-diagnosis function enables quicker access to a failed part and its more accurate troubleshooting.

IN CAR SENSOR

It is a sensor used for detecting room temperature of a vehicle. This sensor converts a given room temperature into a resistance value before entering the data to the automatic air conditioner control unit.

This in car sensor unites the power driven aspirator and the motor fan so that a small amount of room air may be constantly fed to the sensor.

This sensor is provided on the right side of meter cluster.

Scheme 124

AMBIENT SENSOR

This sensor is used for detecting temperature outside the vehicle. It converts a given outside air temperature into a resistance value before entering the data to the automatic air conditioner control unit.

Thermal effects from the condenser and radiator during idling after a run can be measured and offset the automatic amplifier.

This sensor is provided on the side plate situated at upper right side of the condenser.

Scheme 125

The duct sensor is the sensor to detect temperature change of the side of evaporator blower coming by fresh recirculation of intake door or "on" "off" of compressor.

The temperature is converted to resistant rate.

And it works as thermostat to control to prevent freezing of evaporator.

This sensor is installed in the upper case of evaporator.

Scheme 126

SUN SENSOR

It is a photodiode used for detecting quantity of solar radiation. This sensor converts the offset signal generated by changes in the interior temperature (which results from fluctuations in solar radiation) into photoelectric current to enter into the automatic air conditioner control unit.

This sensor is provided at top of the center cluster upper.

Scheme 127

POWER TRANSISTOR

Receiving base current from the automatic air conditioner control unit, the power transistor implements stage-less speed change of the blower fan motor. This transistor is provided on the evaporator.

Scheme 128

MAX HI RELAY

This relay turned on or off by the signal from the automatic air conditioner control unit. As the Max Hi relay is turned on, supply voltage is directly fed to the blower fan motor to select the Max Hi mode.

Scheme 129

ACTUATOR

The actuators are power driven type containing a small motor. Receiving output current from the automatic air conditioner control unit, actuators drive the heater and blower unit mode doors.

Actuators consist of the mode actuator used for switching the mode (blow port selection), the mix actuator used for changing aperture of the air mix door, the intake actuator used for switching the intake mode (fresh air/interior air) actuator.

Scheme 130

The actuator changes the motor speed using the gear and drives each door rotating the output axis united with the sliding contact.

Scheme 131

The mode and mix actuators are common actuators with the built-in potentiometer. For the intake actuator, the contact switch type is selected.

The potentiometer is a register assembled to the printed circuit board of the mix and mode actuators. It detects the air mix door position specified by rotation of the output axis as a ratio of the variable terminal (VM) voltage against the reference voltage (VDD: 5V), then signals the value to the automatic air conditioner control unit.

Scheme 132

MOVEMENT OF MIX ACTUATOR

Position of the air mix door is determined by the controller on the automatic air conditioner control unit.

As the heat or cool side of the controller is grounded, the transistor on the driver is activated and, thus, the motor rotation is turned on. The sliding contact connected to the motor sends the position detection signal from the potentiometer to the automatic air conditioner control unit. As the set temperature and interior temperature are balanced, the controller returns to the neutral and the motor rotation is stopped.

Scheme 133

Scheme 134

MOVEMENT OF MODE ACTUATOR

As target position of the mode door is decided on the controller of the control unit, the control unit reads the position detection signal from the actuator to select the clockwise or counter clockwise motor rotation direction.

Grounding the controller VENT or DEF side after the direction selection activates the transistor on the driver, thus turning on the motor rotation. Accompanying the motor rotation, the sliding contact rotates, too. When the target position is reached, the controller on the control unit returns to the neutral and the motor stops.

Scheme 135

Scheme 136

MOVEMENT OF INTAKE ACTUATOR

The controller on the automatic heater/air conditioner control unit selects an intake mode to be used.

As the Terminal No.5 C-33 is grounded via the sliding contact on the terminal plate, the transistor on the driver is activated, thus turning on the motor rotation. Then, accompanying move of the motor, the sliding contact rotates until grounding of the Terminal No.5 C-33 is removed, thus stopping the motor.

MOVEMENT OF INTAKE ACTUATOR

Scheme 137

INTERIOR TEMPERATURE CONTROL

When the temperature control switch is set to a specific temperature, a signal is sent to the A/C control unit. Other signals are sent to the control unit from the various sensors. This data is analyzed by the control unit which creates a composite data signal that is compared with the signal received from the potentiometer. The result determines the direction of mix actuator rotation.

The mix actuator reacts to the composite air mix door opening angle signal. Opening angle is increased or decreased to maintain the temperature at the selected level.

When the compressor is off, the air mix door moves toward the COOL side. When the compressor turns on, the temperature of the air being discharged from the outlet vents is regulated.

When the temperature control is set to 18°C (65°F), the air mix door moves to the FULL COOL position. When the control is set to 32°C (90° F), the door moves to the FULL HOT position.

In the VENT position, the air mix door moves from FULL COOL to a 60% aperture. This prevents hot air from being discharged into the vehicle.

Scheme 138

IN THE AUTO MODE

1. Automatic operation

When the AUTO switch or the DEF switch is pressed, a signal indicating the forced air volume is sent to the A/C auto-control unit. Other signals are sent to the control unit from the various sensors. This data is analyzed by the control unit which creates a composite data signal. Based on this signal, the base voltage of the power transistor is varied to change the blower voltage. This results in a non-stepped change in blower motor speed.

When the temperature control switch is set to either 18°C (65°F) or 32°C (90°F), blower motor speed is in the MAX-HI mode.

IN THE MANUAL MODE

1. Manual operation When the fan switch is manually set to a specified air volume, a signal is sent to the A/C auto-control-unit. In response to this signal, the auto-control unit controls the blower voltage. When the fan switch is set to HI, the max-hi relay operates to increase blower motor speed to the MAX-HI mode.

Scheme 139

MODE (BLOW PORT) CONTROL

The A/C control unit receives temperature setting data as well as temperature and solar radiation level data from the various sensors. Based on this data, the control unit compiles a composite TMO signal. The TMO signal allows the outlet positions to be changed in a set pattern (VENT ->BI-LEVEL->FOOT ->DEFROST/FOOT).

The mode actuator acts in response to mode position. It compares data signals received from the target mode, the door position, and mode door position to determine the direction of rotation.

If the temperature is set to 18° C (65° F), cool air is discharged from the head outlets. If t he temperature is set to 32°C (90°F), warm air is discharged from the foot outlets.

In manual mode, existing air outlet settings remain unchanged when the temperature is set to 18°C (65°F) or 32° C (90°F).

INTAKE (FRESH AIR/INTERIOR AIR SWITCHING) CONTROL

During automatic operation, the A/C control unit responds to the temperature setting signal together with signals from the various sensors to generate a general signal that controls operation in a prescribed pattern.

If either or both the fan and the cooler are off, air intake is from outside the vehicle.

If the temperature control switch is set to either 18°C (65°F) or 32°C (90°F), the air inside the vehicle is recirculated.

1. Manual switch operation Press the intake switch to change between outside air intake and recirculated inside air.
2. Defrost switch operation Air intake is from outside the vehicle.
3. Mode switch operation

During automatic operation, outside air intake or recirculated inside air is selected as appropriate.

During manual operation or when the DEF mode is selected, air intake is from outside the vehicle.

Scheme 140

COMPRESSOR CONTROL

In the automatic control mode, the automatic air conditioner control unit turns on or off the compressor with the evaporator anti-freeze mechanism using the evaporation sensor. And, when outside air is detected to be low through the outside air temperature sensor signal, the control unit turns off the compressor using the compressor control function.

Manual Control

1. In the automatic control mode, pressing the A/C (air conditioning) switch turns off the compressor.
2. Pressing the DEF mode switch automatically turns on the compressor.

Scheme 141

Heater start-up control occurs when the air discharge mode is in the BI=LEVEL, FOOT, or DEF/FOOT position and the heater core temperature is less than 14°C (58° F).

Air discharge volume remains in the AUTO LO mode until the engine coolant temperature rises above 14°C (58° F). The volume then increases in linear increments to the pre-set level.

Scheme 142

When cooler operation is started with the air discharge mode is in the VENT or B/L position and the in-car temperature higher than 26°C (78°F) (detected by the in-car sensor), cooler start-up control occurs.

For the first 7 seconds of cooler operation, the fan remains OFF. It then switches to AUTO LO. Air discharge volume then increases in linear increments to the pre-set level.

Cooler start-up control occurs the first time the engine is started or the cooler switch is moved from OFF to AUTO. It will not occur during subsequent switch movements.

Scheme 143

PERFORMANCE AND MOVEMENT CHECKLIST FOR AUTOMATIC AIR CONDITIONER RELATED PARTS

Start the engine, and when the engine coolant reached 50°C (122°F) check performance and movement of the related parts according the following checklist.

Scheme 144

Scheme 145

1. Disconnect the in car sensor connector (I-17).
2. Measure resistance between the in car sensor side terminal No. I17-3 and No. I17-4.

Scheme 146

1. Disconnect the sun sensor connector (I-15).
2. Measure the current value on the sun sensor when placed it approximately 15 cm away from 60W incandescent lamp.

Scheme 147

1. Disconnect the connector (C-19) on the ambient sensor.
2. Measure resistance between the ambient sensor side terminals.

Scheme 148

1. Remove the power transistor connector (C-34) from the evaporator assembly.
2. Check the conduction between the power transistor side terminals.

Scheme 149

1. Remove the MAX - HI relay connector (C-35) from the blower assembly.
2. Check the conduction between the MAX - HI relay side terminals.

Scheme 150

1. Turn on the ignition switch (the engine is started). Start the air conditioner in "Auto".
2. Make sure that the in car sensor suctions cigarette smokes and such.

1. Dismount the in car sensor from the automatic heater/air conditioner control unit. Connect (+) end and (-) end of the battery to the aspirator motor side terminals No. I17-1 and No. I17-2, respectively, then check if the motor runs normally.

Scheme 151

HEATER (X-1) AND COMPRESSOR (X-2) RELAY

1. Disconnect relays and check for continuity and resistance between relay terminals.

Scheme 152

THERMOSTAT (X-8) RELAY

1. Disconnect relay and check for continuity and resistance between relay terminals.

Scheme 153

TRIPLE PRESSURE SWITCH

1. Disconnect the connector and check for continuity between pressure switch side connector terminals (1) and (2).
2. Reconnect the connector to activate the A/C switch, and check to see if there is continuity between the chassis side connector terminal (3) and (4) and the fan operates.

Scheme 154

Scheme 155