For 1990-2009 cars

## Cooling Insufficient - Air Conditioning (A/C) Inoperative Oldsmobile

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Are any HVAC DTCs or PCM DTCs stored? | -- | For HVAC DTCs, Go to DTC Table For PCM DTCs, Go to Diagnostic Trouble Code (DTC) List | Go to Step 2
2 |

1. Inspect the outer surface of the condenser for the following items that may restrict the air flow. Remove as necessary.

• | Dirt

• | Leaves

• | Any other material

2. Inspect the area between the condenser and the radiator for the following items that may restrict air flow. Remove as necessary.

• | Dirt

• | Leaves

• | Any other material

3. Inspect the condenser and the refrigerant lines or hoses for the following conditions. Replace damaged components by following the instructions found later in this section.

• | Dents

• | Kinks

• | Other restrictions

4. With the A/C compressor operating, compare the clutch hub speed to the pulley speed. If clutch slippage is indicated, replace the clutch. Refer to Compressor Clutch Plate and Hub Assembly Removal (HT6/HD6)
5. Select the A/C mode.
6. With the engine idling and the A/C compressor operating, inspect the engine cooling fan operation.

Is the left cooling fan operating at low speed and is the right cooling fan operating at high speed?

--

Go to Step 3

Go to Functional Check

3 |

1. Verify that the ambient temperature is not less than the specified value.
2. Idle the engine at normal operating temperature.
3. Open the hood and all of the body doors.
4. Select the AUTO mode (CJ2).
5. Set the temperature control to the MAX COLD position.
6. Set the blower control to the HIGH position.
7. Feel the condenser outlet in front of the expansion (orifice) tube.

Does the condenser outlet feel warm?

21°C (70°F)

Go to Step 5

Go to Step 4

4 | A restriction exists in the high side of the system.

1. Inspect for frost in order to locate the restriction.
2. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
3. Repair as required.
4. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging

Did you complete the repair?

--

System OK

--

5 |

• | Feel the evaporator inlet pipe.

• | Feel the accumulator surface.

Does the evaporator inlet pipe feel noticeably colder than the accumulator surface?

--

Go to Step 6

Go to Step 8

6 | A low refrigerant charge is indicated. Perform a leak test of the A/C system. Refer to Leak Testing Did you find and correct a leak? | -- | Go to Step 7 | Go to Step 8
7 |

1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
2. Repair as required.
3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging

Is the repair complete?

--

System OK

--

8 |

1. Install the J 39500-B to monitor the A/C system high-side and low-side pressures.
2. Observe the low-side pressure gage.

Do the following actions occur?

• | The compressor turns OFF when the pressure drops to nearly the minimum specified value.

• | The compressor turn ON again when the pressure rises to nearly the maximum specified value.

Minimum: 69 kPa (10 psi)

Maximum: 138 kPa (20 psi)

Go to Step 14

Go to Step 9

9 | Inspect the compressor. Does the compressor run continuously? | -- | Go to Step 11 | Go to Step 10
10 | The compressor cycles low or high. Replace the faulty pressure recycling switch. Is the repair complete? | -- | System OK | --
11 |

1. Disconnect the blower motor connector.
2. Observe the following components:

• | The low-side pressure gage

• | The A/C compressor clutch

Does the A/C compressor run continuously while the low-side pressure drops below the specified value?

69 kPa (10 psi)

Go to Step 12

Go to Step 13

12 | Replace the faulty pressure cycling switch. Is the repair complete? | -- | Go to Step 14 | --
13 | One of the following conditions exists:

• | The compressor shuts off when the pressure drops to 138 kPa (20 psi)

• | The pressure never drops to 69 kPa (10 psi) and the A/C compressor runs continuously.

Reconnect the blower motor.

Is the blower motor reconnected?

--

Go to Step 14

--

14 |

1. Record the ambient temperature and the relative humidity.
2. Select the AUTO mode.
3. Set the temperature control to the MAX COLD position.
4. Set the blower control to the HIGH position.
5. Close all of the windows and the doors of the vehicle.
6. Run the engine at idle.
7. Install a thermometer in the vehicle A/C outlet. Wait for 10 minutes.
8. Verify the system performance.

Refer to System Performance Test .

Is the A/C outlet temperature within specified limits?

--

Go to Step 15

Go to Step 16

15 | The refrigeration system is operating properly. Verify that the control portion of the A/C system is operating properly. Refer to Functional Check . Did you perform the functional test? | -- | System OK | --
16 | Observe the compressor operation during the performance test. Does the compressor cycle? | -- | Go to Step 17 | Go to Step 18
17 |

1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
2. Verify that the expansion (orifice) tube is not plugged. Refer to Expansion (Orifice) Tube Replacement
3. Recharge the A/C compressor. Refer to Refrigerant Recovery and Recharging

Is the repair complete?

--

System OK

--

18 | The compressor runs continuously. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging Inspect to see if the expansion (orifice) tube missing? Refer to Expansion (Orifice) Tube Replacement | -- | Go to Step 19 | Go to Step 20
19 |

1. Install a new expansion tube. Refer to Expansion (Orifice) Tube Replacement
2. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging

Is the repair complete?

--

System OK

--

20 | Examine the suction line between the compressor and the pressure cycling switch. Did you find a restriction? | -- | Go to Step 21 | Go to Step 22
21 |

1. Repair as required.
2. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging

Is the repair complete?

--

System OK

--

22 | A system overcharge is indicated. Recover and recharge the A/C system. Refer to Refrigerant Recovery and Recharging Is the repair complete? | -- | System OK | --

## Cooling Insufficient - Air Conditioning (A/C) Inoperative Buick

Table 1: | Gray Area Diagnosis and Service
Table 2: | Striped Area Diagnosis and Service

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Inspect for any stored DTCs. Are any DTCs stored? | -- | Go to Step 2 | Go to Step 3
2 | Correct any stored DTCs. Refer to DTC Table . Are all of the DTCs corrected? | -- | System OK | --
3 | Connect the J 39500-B Are pressures above the specified value? | 350 kPa (50 psi) | Go to Step 5 | Go to Step 4
4 | The system is undercharged.

1. Add 1 lb of refrigerant.
2. Perform the leak check procedure. Refer to Leak Testing .
3. Repair the leak.
4. Recheck the system performance.

Is the cooling insufficient?

--

Go to Step 5

System OK

5 |

1. Perform a visual inspection. Inspect for the following conditions:

• | A blown A/C fuse

• | A disconnected A/C clutch wire

• | Condenser and radiator restrictions

• | Correct A/C clutch rotation

2. Read the DCS for bulletins or hints.
3. Verify that the ambient temperature is not less than the specified value.
4. Idle the engine at normal operating temperature.
5. Turn the A/C to the ON position.
6. Set the temperature control to the MAX COLD position.
7. Set the blower control to the HIGH position.
8. Record the A/C pressures and temperatures.

Refer to System Performance Test . Are the A/C pressures and temperatures within specified limits?

5°C (41°F)

Go to Step 6

Go to Step 8

6 | Did the customer indicate that either high temperature or high humidity caused the problem? | -- | Go to Step 7 | System OK
7 | Possible causes:

• | Low charge

• | Air in the system

1. Perform the leak test. Refer to Leak Testing .
2. Recover and recharge the A/C system. Refer to Refrigerant Recovery and Recharging

Did you complete the repair?

--

System OK

--

8 | Does the A/C compressor clutch engage? | -- | Go to System Performance Test | Go to HVAC Compressor Clutch Does Not Engage

### High Side vs. Low Side Pressure Table

#### Gray Area Diagnosis and Service

Problem | Action
--- | ---
DEFINITION: Inspect the following components if the pressure values intersect in the gray area of the chart.
The condenser operates improperly. | Improper condenser operation may result from the following conditions:

• | Extremely high ambient humidity

• | Insufficient air flow across the condenser

• | Damaged or dirty condenser fins

• | A faulty fan relay

Clean or repair the components as necessary.

A high side refrigerant restriction exists. |

1. Feel the liquid line in front of the expansion (orifice) tube. If the line feels cold, a restriction in the high side may be present.
2. Visually inspect for a frost spot in order to locate the restriction. Remove any restrictions as necessary.

The refrigerant system is overcharged. The following conditions are present:

• | A high discharge pressure exists.

• | A high suction pressure exists.

The clutch may cycle ON/OFF (see note). This condition may result in a noisy compressor.

1. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
2. Inspect the expansion (orifice) tube for a blockage. Refer to Expansion (Orifice) Tube Replacement Clean or replace the tube as necessary.
3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
4. Inspect the system for leaks. Refer to Leak Testing .

• | The expansion (orifice) tube is blocked (low suction pressures exist).

• | Air is in the system. The following conditions are present:

- | A high discharge pressure exists.

- | A high suction pressure exists.

1. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
2. Inspect the expansion (orifice) tube for a blockage. Refer to Expansion (Orifice) Tube Replacement Clean or replace the tube as necessary.
3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
4. Inspect the system for leaks. Refer to Leak Testing .

NOTE: V5 clutch cycling may occur when the discharge pressure exceeds 2758 kPa (400 psi).

#### Striped Area Diagnosis and Service

Problem | Action
--- | ---
DEFINITION: Inspect the following components if pressure values intersect in the striped area of the chart.
The compressor has internal damage. |

• | If the suction and the discharge pressures are equal and do not change when you turn the A/C mode ON and OFF, then the compressor may be internally damaged.

• | Excess heat at the clutch surfaces or a free wheeling clutch driver are signs of internal compressor damage.

• | When replacing the compressor, follow the component replacement procedures in order to maintain the correct oil charge in the system.

The expansion (orifice) tube is missing. |

1. Feel the liquid line behind the expansion (orifice) tube.

• | If the line is warm, recover the refrigerant. Refer to Refrigerant Recovery and Recharging . Inspect the system for proper installation of the expansion tube. Refer to Expansion (Orifice) Tube Replacement . Reinstall the tube if necessary.

• | If the expansion tube or the O-ring is missing, replace the expansion tube.

2. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

The compressor is at minimum stroke. |

#### High Load Test

If the compressor discharge pressures remain only 69-207 kPa (10-30 psi) above the suction pressure, then the compressor may be at minimum stroke. Perform the following procedure:

1. Run the engine at approximately 3000 RPM for 3 minutes until the pressures return to normal.
2. During this period, cycle the mode lever from the VENT position to the A/C position every 20 seconds.
3. Observe the pressure. If no change occurs, perform the Low Load Test.

The compressor control valve is set improperly. |

#### Low Load Test

The low load test procedure creates a low cooling load. This condition causes the V5 compressor to go toward minimum stroke. Use this test procedure for evaluation of the control valve set point.

1. Start the engine.
2. Run the engine at a fast idle.
3. Open the hood. Close all of the windows and the doors.
4. Select the A/C mode.
5. Set the blower control to the LOW position.
6. Set the temperature control to the MAX COLD position.
7. Record and evaluate the test results:

• | If the suction pressure is within 172-241 kPa (25-35 psi), then the control valve is functioning properly.

• | If the suction pressure outside the range of 172-241 kPa (25-35 psi), then replace the control valve.

The refrigerant system is undercharged. | The refrigerant system may be undercharged when the suction pressure is below 241 kPa (35 psi) during the High Load Test. If the charge is low, the suction line before the accumulator will be warm.

1. Add 1 lb of refrigerant.
2. Inspect the suction pressure again.

Ensure that the pressure values are within the white (normal) area on the chart. If so, find the source of the refrigerant leak. Repair the leak as necessary.

3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

The expansion (orifice) tube is blocked. |

1. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
2. Inspect the expansion (orifice) tube for a blockage. Refer to Expansion (Orifice) Tube Replacement .
3. Clean or replace the tube as necessary.
4. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
5. Inspect the system for leaks. Refer to Leak Testing .