GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 Body and Accessories 🢒 Body Control System 🢒 Cooling Insufficient - Air Conditioning (A/C) Inoperative
Table 1: Gray Area Diagnosis and Service

Step

Action

Value(s)

Yes

No

1

Inspect for any stored DTCs.

Are any DTCs stored?

--

Go to Step 3

Go to Step 2

2

Connect the J 39500-B .

Are the pressures above 350 kPa (50 psi)?

--

Go to Step 4

Go to Step 8

3

Correct any stored DTCs. Refer to DTC Table .

Does the complaint persist?

--

Go to Step 1

System OK

4

Inspect and correct for a blown Air Conditioner (A/C) fuse. Refer to Circuit Protection - Fuses in Body and Accessories.

Does the complaint persist?

--

Go to Step 5

System OK

5

Inspect and correct for the following conditions:

    • Disconnected A/C clutch wire
    • Proper A/C clutch rotation

Refer to HVAC Compressor Clutch Does Not Engage . Does the complaint persist?

--

Go to Step 6

System OK

6

Inspect and correct for the following conditions:

    • Condenser restrictions refer to Condenser Replacement .
    • Radiator restrictions

Refer to Flushing or Radiator Replacement in Engine Cooling.

Does the complaint persist?

--

Go to Step 7

System OK

7

Read the DCS for Bulletins and Hints.

Follow the procedures indicated.

Does the complaint persist?

--

Go to Step 10

System OK

8
  1. Add 0.453 kg (1 lb) of refrigerant. Refer to Refrigerant Recovery and Recharging and Handling Refrigerant R-134a .
  2. Perform a leak check. Refer to Leak Testing .

Did you find a leak?

--

Go to Step 9

Go to Step 1

9
  1. Repair the leak.
  2. Inspect the system performance. Refer to System Performance Test .

Does the complaint persist?

--

Go to Step 2

System OK

10

Perform an A/C Performance Check using the following steps:

  1. Ensure that the ambient temperature is at least 5°C (41°F).
  2. Ensure that the engine is idling at normal operating temperature.
  3. Turn the A/C to the ON position.
  4. Select the coldest setting.
  5. Select the MAX blower speed.
  6. Record the A/C pressures.
  7. Record the A/C temperatures.
  8. Refer to System Performance Test .

Does the A/C performance meet the requirement on the Performance Chart?

--

Go to Step 11

Go to High Side vs. Low Side Pressure Chart

11

Was the customer complaint made due to high temperature and/or high humidity?

--

Go to Step 12

System OK

12

Perform a leak test. Refer to Leak Testing .

Did you find a leak?

--

Go to Step 13

System OK

13

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

Does the complaint persist?

--

Go to Step 10

System OK

High Side vs. Low Side Pressure Chart
Object Number: 247012 Size: LF

Gray Area Diagnosis and Service

Problem

Action

Important: The V5 clutch may cycle if the discharge pressure exceeds 2758 kPa (400 psi).

Improper condenser operation

Improper condenser operation may result from one of the following causes:

    • Extremely high ambient humidity
    • Insufficient air flow across condenser
    • Damaged or dirty condenser fins
    • Faulty fan relay

High side refrigerant restriction
  1. Feel liquid line before expansion tube (orifice). A cold line indicates restriction in the high side.
  2. Inspect for a frost spot in order to locate the restriction.
  3. Repair the line as necessary.

Refrigerant system overcharged (high discharge and high suction pressures)

The clutch may cycle ON/OFF and cause compressor noise.

Expansion tube (orifice) blocked

Low suction pressures.

Air in system (High discharge and high suction pressures).
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  2. Inspect the expansion (orifice) tube for blockage. Refer to Expansion (Orifice) Tube Replacement .
  3. Clean or replace the tube as required.
  4. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
  5. Leak test the system. Refer to Leak Testing .

Cooling Insufficient - A/C Inoperative

Problem

Action

The compressor is damaged internally.
    • If suction and discharge pressure are equal and do not change when the A/C mode is turned ON and OFF, 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 correct oil charge in the system.

The expansion tube (orifice) is missing.
  1. Feel the liquid line after the expansion tube.
  2. If the line is warm, recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  3. Inspect for proper installation of the expansion tube. Refer to Expansion (Orifice) Tube Replacement .
  4. Clean or replace as necessary.
  5. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

The Compressor runs at minimum stroke.
    • If the compressor discharge pressures remain only 10-30 psi above the suction pressure, the compressor may be at minimum stroke.
    • Run the engine at approximately 3000 RPM for 3 minutes until pressures become normal. During this period, cycle the mode lever from vent to A/C every 20 seconds. If there is no change, then perform the control valve low load test below.

The compressor control valve is set improperly.

The low load test creates a low cooling load that causes the V5 compressor to go toward minimum stroke. Minimum stroke is necessary in order to evaluate the control valve set point. Perform the low load test using the following procedure:

  1. Start the engine
  2. Run the engine at a fast idle.
  3. Open the hood.
  4. Close the windows and the doors.
  5. Set the A/C controls to LOW blower and MAX cooling.
  6. Record the test results.
  7. Evaluate the test results as follows:
    8. • If suction pressure is 25-35 psi, then the control valve is functioning properly.
    • If the suction pressure is outside the limits of 25-35 psi, then replace the control valve.

The refrigerant system is undercharged.
  1. The refrigerant may be undercharged when the suction pressure is below 35 psi during the high load test.
  2. The suction line before the accumulator will be warm if the charge is low.
  3. Add 1 lb of refrigerant.
  4. Recheck the pressure. Verify that the pressure is in the white area on the chart. Then find and correct the leak.
  5. Evacuate the system.
  6. Charge the system with the correct amount of refrigerant.

The expansion tube (orifice) is blocked.
  1. Feel the liquid line after the expansion tube.
  2. If the line is warm, recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  3. Inspect for proper installation of the expansion tube. Refer to Expansion (Orifice) Tube Replacement .
  4. Clean or replace as necessary.
  5. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .