DEFINITION:

The V5 compressor is a variable displacement compressor which matches air conditioning demand by changing the stroke rather than cycling the clutch. A control valve is located in the rear head of the compressor. The control valve senses the compressor low side pressure and causes the compressor mechanism to change stroke.

During extended periods of shutdown, liquid refrigerant collects in the compressor crankcase. This is normal. The cooling action may be delayed for up to 2 minutes until the refrigerant is pumped from the compressor crankcase.

Because the V5 compressor always runs and the system does not cycle, these diagnostic procedures differ from those used for fixed displacement systems. Use these procedures in order to avoid needlessly replacing A/C components.

Certain conditions which are normal to proper air conditioning system operation may lead an owner to wrongly suspect a problem.

The air discharged from the air conditioning system may not feel as cold as expected under conditions of high humidity. The reason is that the vaporized moisture in humid air heats more effectively than dry air does, making the humid air harder to cool.

In terms of overall comfort, however, the dryer dehumidified air coming from the air conditioning system during hot, humid weather evaporates more moisture on a person's skin, providing more of a cooling effect than might be felt from cooler but more humid air.

This fact should be explained to an owner if no mechanical cause is found for a persistent complaint of insufficient cooling.

Did you perform the A/C System Performance Test?

Go to Step 2

Go to Air Conditioning (A/C) System Performance Test

1. Inspect the A/C fuse for an open. Refer to Circuit Testing and Wiring Repairs in Wring Systems.
2. Inspect the compressor clutch connector for an open or a poor connection.

Did you find and correct the condition?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 3

1. Inspect the temperature cable operation.
2. Move the temperature control rapidly from the coldest to the hottest position.
3. Listen for the door hitting at each end.
4. Repair as necessary. Refer to Temperature Control Cable Adjustment in HVAC Systems - Manual.

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 4

Inspect the blower motor for proper operation. Refer to Symptoms - HVAC Systems - Manual .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 5

Inspect the cooling fan system for proper operation. Refer to Symptoms - Engine Cooling in Engine Cooling.

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 6

1. Inspect the condenser for restricted air flow.
2. Clean and/or repair the condenser as necessary. Refer to Condenser Replacement .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 7

Inspect for a slipping, damaged or missing compressor drive belt. Refer to Drive Belt Replacement in Engine Mechanical.

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

Go to Step 8

1. The ambient air temperature must be at least 16°C (60°F).
2. The engine should be at operating temperature.
3. Ensure that the R-134a manifold gage set is properly calibrated.
4. Connect the High and Low side pressure gages to the service ports on the vehicle.
5. Both pressures should be almost equal to each other.

Are both pressures 345 kPa (50 psi) or higher?

Go to Step 10

Go to Step 9

1. Leak test the system. Refer to Leak Testing .
2. Add 0.45 kg (1.0 lb) of refrigerant if necessary.
3. Evacuate and recharge the system. Refer to Refrigerant Recovery and Recharging .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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1. Run the engine at idle.
2. Set the air mode to the FRESH position.
3. Set the blower speed to HIGH.
4. Set the temperature control to the coldest position.
5. Depress the A/C switch to the ON position.

Does the compressor clutch engage?

Go to Step 11

Go to HVAC Compressor Clutch Does Not Engage

Inspect the system for the following conditions:

Is there noise from the compressor?

Go to Step 12

Go to Step 13

Repair or replace the compressor. Refer to the following:

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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Important: This test is designed for typical garage conditions: 21-32°C (70-90°F) and no sun load. Normal discharge air temperature is typically at least 7°C (20°F) cooler than ambient temperature. This test is designed to create enough cooling load to cause the V5 to operate at full stroke. This procedure must be followed exactly for accurate test results.

1. The ambient air temperature must be at least 16°C (60°F).
2. Close all vehicle doors and windows.
3. Set the air mode to the FRESH position.
4. Set the blower speed to High.
5. Set the temperature control to the coldest position.
6. Depress the A/C switch to the ON position.
7. Run the engine at idle for 5 minutes.
8. Feel the liquid line on both sides of the orifice tube.

Is there a noticeable temperature difference?

Go to Step 15

Go to Step 14

1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
2. Inspect for a missing or damaged expansion (orifice) tube or O-ring. Refer to Expansion (Orifice) Tube Replacement .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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Important: Humidity and temperature variables can create borderline diagnostic conditions and increase the pressure range of a normally operating system. If possible, test a known good system in order to determine if the pressures are normal for the climatic conditions encountered.

1. Operate the A/C system for 5 minutes or more.
2. Record the High and Low side pressures while the cooling fans are running.
3. Locate the intersection of the High and Low side pressures on the diagnostic table.

Do the pressures intersect in the grey side of the table?

Go to Step 16

Go to Step 19

1. The A/C system is still operating.
2. Close the vehicle doors and windows.
3. Open the hood.
4. The engine cooling fans must be running.
5. Feel the liquid line between the condenser and the expansion (orifice) tube. The line should feel warm to the touch.

Does the line feel cold?

Go to Step 18

Go to Step 17

The refrigerant system is overcharged or there is air in the system. Evacuate and recharge. Refer to Refrigerant Recovery and Recharging and Leak Testing .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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1. Repair the restriction in the High side of the refrigerant system. Refer to Leak Testing and Refrigerant Recovery and Recharging .
2. Visually inspect the line/pipe for a frost spot in order to locate the restriction.

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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Do the pressures intersect in the striped side of the table?

Go to Step 20

Go to Step 28

Are the compressor High and Low side pressures within 207 kPa (30 psi) of each other?

Go to Step 21

Go to Step 23

1. The ambient air temperature must be at least 16°C (60°F).
2. Close all vehicle doors and windows.
3. Set the air mode to the FRESH position.
4. Set the blower speed to HIGH.
5. Set the temperature control to the coldest position.
6. Depress the A/C switch to the ON position.
7. Run the engine at 3000 RPM.
8. Cycle the A/C switch ON and OFF every 20 seconds for 3 minutes.

Are the compressor High and Low side pressures within 207 kPa (30 psi) of each other?

Go to Step 22

Go to Step 13

1. Inspect the compressor for seizure.
2. Stop the engine.
3. Disengage the compressor clutch.
4. Rotate the compressor clutch driver, not the pulley, by hand.

Does the compressor clutch driver turn freely by hand?

Go to Air Conditioning Compressor Replacement

Go to Step 26

Is the Low side pressure 172-241 kPa (25-35 psi)?

Go to Step 24

Go to Step 26

The refrigerant is undercharged. Add 0.40 kg (14 oz) of refrigerant.

Does the cooling performance improve?

Go to Step 9

Go to Step 25

1. Discharge the system.
2. Inspect for a plugged expansion (orifice) tube or a restriction in the High side of the system.
3. Clear the lines.
4. If only light debris is present in the tube, clean the tube using compressed air.
5. Clean or replace the expansion (orifice) tube as necessary. Refer to Expansion (Orifice) Tube Replacement .

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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Important: This control valve test is designed to create a low cooling load which causes the V5 to operate at less than full stroke. This procedure must be followed exactly for accurate test results.

1. Run the engine for 5 minutes at 2000 RPM.
2. Set the blower speed to LOW.
3. Set the temperature control to the coldest position.
4. Set the fresh/recirc door to the RECIRC position.
5. Depress the A/C switch to the ON position.
6. Close the vehicle's windows and doors.
7. Open the hood.

Is the Low side pressure 172-241 kPa (25-35 psi)?

Go to Step 13

Go to Step 27

Replace the control valve. Refer to the following:

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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The pressures intersect in the white or normal side of the table. The refrigeration system components are functioning properly. Inspect for restrictions or leakage within the heater case. Refer to Air Recirculation Malfunction in HVAC Systems - Manual.

Is the repair complete?

Go to Air Conditioning (A/C) System Performance Test

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High Side Pressure Above Specifications

High Side Pressure Below Specifications

Low Side Pressure Above Specifications

Low Side Pressure Below Specifications

Center Air Outlet Temperature Above Specifications

Center Air Outlet Temperature Below Specifications

There is a blower malfunction causing insufficient air volume. Refer to Blower Motor Inoperative or Blower Motor Malfunction .