GM Service Manual Online
For 1990-2009 cars only
Table 1: A/C Performance

Test Description

This test measures the operating efficiency of the A/C system under the following conditions:

    • The current ambient air temperature
    • The current relative humidity
    • The high side pressure of the A/C system
    • The pressure at the low-pressure side of the refrigeration system
    • The temperature of the air being discharged into the passenger compartment

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the A/C system has at least the minimum refrigerant charge required to operate the A/C system without damage.

  2. This step measures the performance of the A/C system.

  3. This step is to allow for vehicle variations as well as high ambient temperatures.

Step

Action

Value(s)

Yes

No

Important: 

   • The ambient air temperature must be at least 60°F (16°C) .
   • Do not induce additional air flow across the front of the vehicle during the test.
   • If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test.

1

  1. Park the vehicle inside or in the shade.
  2. Open the windows in order to ventilate the interior of the vehicle.
  3. If the A/C system was operating, allow the A/C system to equalize. Allow about 2 minutes.
  4. Ensure that the ignition key is in the OFF position.
  5. Install the J 43600 ACR 2000 Air Conditioning Service Center.
  6. Record the ambient air temperature displayed on the J 43600 .
  7. Record readings of the low and high side STATIC pressures.

Are both the low and high side pressures within the specified value?

Above 16°C (60°F) - 345 kPa (50 psi)

Above 24°C (75°F) - 483 kPa (70 psi)

Above 33°C (90°F) - 690 kPa (100 psi)

Go to Step 2

Go to Leak Testing

2

    Important: Record the relative humidity and the ambient air temperature AT THE TIME OF THE TEST.

  1. Close the vehicle doors and windows.
  2. Open the driver door window 12.7-15.2cm (5-6 in).
  3. Set the HVAC control to the following positions:
  4. • Max A/C
    • The blower control to the highest position
    • The HVAC control assembly to discharge air through the A/C outlets
    • The temperature control to the coldest position
    • All A/C outlets OPEN
  5. Install temperature to the J 43600 in the left and right center A/C air outlets.
  6. Apply the parking brake.
  7. Place the transaxle/transmission in one of the following positions:
  8. • PARK - Automatic
    • NEUTRAL - Manual
  9. Start the engine and allow to idle.
  10. Operate the A/C system for 5 minutes.
  11. Inspect for the following:
  12. •  Abnormal frost areas
    • Unusual noises

    Important: In order to capture the correct information, press the RESET button of the J 43600 before pressing the PRINT button after the 5 minute operating time.

  13. Record the following information:
  14. • The outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  15. Compare the low and high side pressures and the output temperatures to the table below.

Does all the data recorded fall within the specified ranges of the table below?

--

Go to Step 4

Go to Step 3

3

If the pressures and temperatures recorded do not fall within the specified ranges:

  1. Continue to operate the A/C system for an additional 5 minutes.
  2. Record the pressures and temperatures again.
  3. Compare the low and high side pressures and the output temperature to the table below.

Does all the data recorded fall within the specified ranges of the table below?

--

Go to Step 8

Go to Step 4

4

Do the high and low side pressures fall within the specified ranges but the outlet temperatures do not?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone A

Go to Step 5

5

Is the low side pressure higher than the specified range and the high side pressure within or lower than the specified range?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone B

Go to Step 6

6

Are the low and high side pressures both higher than the specified ranges?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone C

Go to Step 7

7

Is the low side pressure within or lower than the specified range and the high side pressure higher than the specified range?

--

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone D

Go to Step 8

8

Operate the system in order to verify the test results.

Did you find the same results?

--

System OK

Go to Symptoms - HVAC Systems - Manual in HVAC - Manual System

A/C System Pressure -- Zone Classification


Object Number: 708666  Size: MF

A/C Performance

Ambient Air Temperature

Relative Humidity

Service Port Pressure

Maximum Left Center Discharge Air Temperature

Low Side

High Side

13-18°C (55-50°F)

0-100%

222-252 kPa (32-37 psi)

1080-129 kPa (157-187 psi)

13°C (55°F)

19-24°C (66-75°F)

Below 40%

231-261 kPa (34-38 psi)

1220-1460 kPa (177-212 psi)

14°C (57°F)

Above 40%

251-281 kPa (36-41 psi)

1220-1500 kPa (177-218 psi)

16°C (61°F)

25-29°C (76-85°F)

Below 35%

251-281 kPa (36-41 psi)

1360-1590 kPa (197-231 psi)

16°C (61°F)

35-60%

259-289 kPa (28-42 psi)

1380-1620 kPa (200-235 psi)

17°C (63°F)

Above 60%

275-305 kPa (40-44 psi)

1390-1680 kPa (202-244 psi)

19°C (66°F)

30-35°C (86-95°F)

Below 30%

276-306 kPa (40-44 psi)

1470-1730 kPa (213-251 psi)

19°C (66°F)

Above 30%

287-317 kPa (42-46 psi)

1500-1800 kPa (218-261 psi)

20°C (68°F)

36-41°C (96-105°F)

Below 20%

297-327 kPa (43-47 psi)

1590-1840 kPa (231-267 psi)

21°C (70°F)

20-40%

309-339 kPa (45-49 psi)

1320-1930 kPa (235-280 psi)

22°C (72°F)

Above 40%

320-350 kPa (46-51 psi)

1690-2020 kPa (245-293 psi)

24°C (75°F)

42-46°C (106-115°F)

Below 20%

319-349 kPa (46-51 psi)

1720-1960 kPa (250-285 psi)

23°C (73°F)

Above 20%

332-362 kPa (48-53 psi)

1760-2070 kPa (255-300 psi)

24°C (75°F)

47-49°C (116-120°F)

Below 30%

339-369 kPa (49-54 psi)

1880-2090 kPa (273-303 psi)

25°C (77°F)