GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Optra 🢒 HVAC 🢒 HVAC - Manual 🢒 Too Hot in Vehicle

Important: Perform this test under garage conditions with the air temperature at 21-32°C (70-90°F), and no sun load. Follow this test carefully for accurate results.

Important: Perform this test exactly as described to obtain accurate results.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: Component Connector End Views

1

Record the customer's complaint.

Can you verify the customer's complaint?

--

Go to Step 2

System OK

2
  1. Inspect the A/C fuse.
  2. Inspect the blower fan operation.
  3. Inspect the engine cooling fan operation.
  4. Inspect the A/C compressor belt.
  5. Inspect the A/C condenser for restricted airflow.
  6. Inspect the clutch coil connection.
  7. Repair or replace any components, as needed.
  8. Inspect the discharge air temperature with the A/C turned ON.

Is the discharge air temperature normal?

At least 7°C (12°F) below ambient air temperature

System OK

Go to Step 3

3
  1. Turn the ignition switch to LOCK.
  2. Connect the high pressure and the low pressure gages.

Do both pressures measure within the specified range?

69-345 kPa (10-50 psi)

Go to Step 4

Go to Step 5

4
  1. Inspect the A/C system for leaks.
  2. Repair any refrigerant leaks, as needed.
  3. Recover, evacuate, and recharge the A/C system.
  4. Observe the 2 pressure gages.

Do both pressures measure greater than the specified value?

345 kPa (50 psi)

Go to Step 7

--

5

Observe the 2 pressure gages.

Do both pressures measure less than the specified value?

69 kPa (10 psi)

Go to Step 6

Go to Step 7

6
  1. Add 0.45 kg (1 lb) of refrigerant R-134a.
  2. Inspect the A/C system for leaks.
  3. Repair any refrigerant leaks, as needed.
  4. Recover, evacuate, and recharge the A/C system.
  5. Observe the 2 pressure gages.

Do both pressures measure above the specified value?

345 kPa (50 psi)

Go to Step 7

--

7
  1. Start the engine and allow it to run at idle.
  2. Set the A/C controls to the following positions:
    3. • The A/C switch to ON
    • The fresh air control switch to fresh air, indicator lamp OFF
    • The blower motor to 4
    • The temperature to full cold

Does the A/C compressor clutch engage?

--

Go to Step 8

Go to Step 10

8
  1. Inspect for a knocking noise from the A/C compressor.
  2. Cycle the A/C compressor ON and OFF in order to verify the source of the noise.

Do you hear a loud knocking noise?

--

Go to Step 9

Go to Step 13

9
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor.
  3. Evacuate and recharge the A/C system.
  4. Inspect the A/C system for leaks.

Is the compressor running normally?

--

Go to Step 13

--

10
  1. Turn the ignition switch to LOCK.
  2. Disconnect the A/C compressor clutch coil connector.
  3. Connect a jumper wire from ground to 1 A/C compressor clutch coil terminal.
  4. Connect a fused jumper wire from the positive battery terminal to the other A/C compressor clutch coil terminal.

Does the A/C clutch engage?

--

Go to Step 11

Go to Step 12

11

Repair the electrical circuit to the A/C compressor clutch coil.

Does the A/C clutch engage?

--

Go to Step 8

--

12

Replace the A/C compressor clutch coil.

Did you complete the replacement?

--

Go to Step 8

--

13

  1. Close all of the vehicle's windows and doors.
  2. Set the A/C controls to the following positions:
    3. • The A/C switch to ON
    • The fresh air control switch to fresh air, indicator lamp OFF
    • The blower motor to 4
    • The temperature to full cold
  3. Start the engine and allow it to run at idle for 5 minutes.
  4. Feel the evaporator inlet and outlet pipes.

Is there a noticeable difference in the temperature of the evaporator inlet and outlet pipes?

--

Go to Step 15

Go to Step 14

14
  1. Turn the ignition switch to LOCK.
  2. Recover the A/C system refrigerant.
  3. Inspect the high-pressure pipe for an obstruction.
  4. Inspect the expansion valve for an obstruction or a malfunction.
  5. Repair the obstruction or replace the expansion valve as needed.
  6. Evacuate and recharge the A/C system.
  7. Inspect the A/C system for leaks.
  8. Note the discharge air temperature with the A/C ON.

Is the discharge temperature normal?

At least 7°C (12°F) below ambient air temperature

Go to Step 15

Go to Step 13

15
  1. Record the low and the high side pressures after the A/C system has been operating for 5 minutes or more with the engine cooling fan ON.
  2. Locate the intersection of the low and high side pressures. Refer to the Low and High Side Pressure Relationship Chart in Symptoms - HVAC Systems - Manual .

Do the low and high side pressures intersect in the white area of the chart?

--

System OK

Go to Step 16

16

Inspect the low and high side pressures.

Do the low and high side pressures intersect in the gray area of the chart?

--

Go to Step 17

Go to Step 20

17

Feel the liquid pipe between the condenser and the expansion valve.

Is the pipe cold?

--

Go to Step 18

Go to Step 19

18
  1. Inspect the condenser for any restriction of the airflow.
  2. Inspect the cooling fans for proper operation.
  3. Remove the restriction or repair the fans, as required.

Is the pipe temperature normal now?

At least 7°C (12°F) below ambient air temperature

Go to Step 13

--

19
  1. Recover, evacuate, and recharge the A/C system.
  2. Inspect the A/C system for leaks.

Is the system free from leaks?

--

Go to Step 13

--

20

Observe the readings on the pressure gages.

Are the A/C compressor low and high side pressures within the specified value of each other?

207 kPa (30 psi)

Go to Step 21

Go to Step 26

21
  1. Run the engine at 3,000 RPM.
  2. Set the A/C controls to the following positions:
    3. • The A/C switch to ON
    • The fresh air control switch to fresh air
    • The blower motor to 4
    • The temperature to full cold
  3. Close all of the vehicle's windows and doors.
  4. Turn the A/C switch ON and OFF every 20 seconds for 3 minutes.

Are the A/C compressor low and high side pressures within the specified value of each other?

207 kPa (30 psi)

Go to Step 22

Go to Step 13

22

Observe the pressure rise on both gages and the temperatures of both the compressor suction pipe and the discharge pipe.

Is the pressure rise on both gages slow and the suction pipe warm with the discharge pipe very hot?

--

Go to Step 25

Go to Step 23

23
  1. Turn the ignition switch to LOCK.
  2. Make sure the compressor clutch is disengaged.
  3. Attempt to turn the clutch driver, not the pulley.

Can you turn the clutch driver freely by hand?

--

Go to Step 25

Go to Step 24

24
  1. Start the engine.
  2. Observe the low side pressure gage while running the engine between 3,000-3,800 RPM.

Does the low side pressure rise rapidly?

--

Go to Step 32

Go to Step 25

25
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor.
  3. Evacuate and recharge the A/C system.

Is the compressor functioning normally?

--

Go to Step 13

--

26

Measure the low side pressure.

Does the low side pressure measure within the specified range?

172-241 kPa (27-38 psi)

Go to Step 27

Go to Step 32

27

Feel the high side pipe leading up to the expansion valve connecting block.

Is the pipe cold before the connecting block?

--

Go to Step 28

Go to Step 29

28
  1. Inspect for a restriction in the high side pipe before the expansion valve.
  2. Repair or replace the high side pipe.

Is the pipe performing normally?

--

Go to Step 13

--

29

Add the specified amount of refrigerant to the A/C system.

Does the cooling performance improve?

0.40 kg (14 oz)

Go to Step 30

Go to Step 31

30
  1. Inspect the A/C system for leaks.
  2. Repair any refrigerant leaks, as needed.
  3. Evacuate and recharge the A/C system.
  4. Inspect the A/C system for leaks.

Is the system free from leaks?

--

Go to Step 13

--

31
  1. Recover the refrigerant.
  2. Inspect the expansion valve for obstructions.
  3. Repair or replace the expansion valve, as required.
  4. Evacuate and recharge the system.
  5. Inspect the A/C system for leaks.

Is the system free from leaks?

--

Go to Step 13

--

32

  1. Run the engine for 5 minutes at 2,000 RPM.
  2. Set the A/C controls to the following positions:
    3. • The A/C switch to the ON position
    • The fresh air control switch to recirculate, indicator lamp ON
    • The blower motor to 1
    • The temperature to full cold
  3. Close all of the vehicle's windows and doors.
  4. Open the vehicle hood.

Does the low side pressure measure within the specified range?

172-241 kPa (25-35 psi)

Go to Step 13

Go to Step 33

33
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor control valve.
  3. Evacuate and recharge the A/C system.
  4. Inspect the A/C system for leaks.

Is the system free from leaks?

--

Go to Step 13

--