GM Service Manual Online
For 1990-2009 cars only

Air Conditioning (A/C) System Performance Test LY7

Table 1: A/C Performance Table

Test Description

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

    • The current ambient air temperature (AAT)
    • The current relative humidity
    • The high side pressure of the A/C system
    • The low side pressure of the A/C 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 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 (AATs).

Step

Action

Values

Yes

No

Important: 

   • The ambient air temperature (AAT) must be at least 16°C (60°F).
   • 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 for about 2 minutes.
  4. Turn OFF the ignition.
  5. Install the J 43600 ACR 2000 Air Conditioning Service Center.
  6. Record the ambient air temperature (AAT) 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 AAT AT THE TIME OF THE TEST.

  1. Close the vehicle doors and windows.
  2. Open the driver door window 12.7-15.2 cm (5-6 in).
  3. Select the following HVAC control setting:
  4. • The A/C is ON.
    • The coldest temperature setting
    • The maximum blower speed
    • Recirculation mode
    • The instrument panel (I/P) outlet mode
    • All I/P outlets are OPEN
  5. Install the temperature probes of the J 43600 in the left and right center panel air outlets.
  6. Apply the parking brake.
  7. Place the transmission in PARK.
  8. Start the engine.
  9. Operate the A/C system for 5 minutes.
  10. Inspect A/C components for the following conditions:
  11. •  Abnormal frost areas
    • Unusual noises

    Important: When performing this step it is necessary to press the RESET button on the J 43600 before pressing the PRINT button.

  12. Print the following information:
  13. • The panel outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  14. Compare the low and high side pressures and the panel output temperatures to the A/C performance table below.

Does all the data recorded fall within the specified ranges of the A/C performance table?

--

Go to Step 8

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 panel output temperature to the A/C performance table.

Does all the data recorded fall within the specified ranges of the A/C performance table?

--

Go to Step 8

Go to Step 4

4

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

--

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

Go to Step 5

5

Is the low side pressure greater than the specified range, but the high side pressure is within or less 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 greater than the specified ranges?

--

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

Go to Step 7

7

Is the high side pressure greater than the specified range, but the low side pressure is within or less 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 or to Symptoms - HVAC Systems - Automatic

A/C System Pressure - Zone Classification

A/C System Pressure - Zone Classification


Object Number: 1538562  Size: MF

A/C Performance Table

Ambient Air Temperature

Relative Humidity

Service Port Pressure

Maximum Left Center Discharge Air Temperature

Low Side

High Side

13-18°C (55-65°F)

0-100%

158-254 kPa (23-37 psi)

881-1288 kPa (128-187 psi)

18°C (64°F)

19-24°C (65-75°F)

Below 40%

151-227 kPa (22-33 psi)

923-1329 kPa (134-193 psi)

15°C (59°F)

Above 40%

172-275 kPa (25-40 psi)

1047-1460 kPa (152-212 psi)

20°C (68°F)

25-29°C (75-85°F)

Below 35%

158-241 kPa (25-35 psi)

1157-1481 kPa (168-215 psi)

18°C (63°F)

35-50%

186-254 kPa (27-37 psi)

1233-1522 kPa (179-221 psi)

19°C (66°F)

Above 50%

199-282 kPa (29-41 psi)

1281-1598 kPa (186-232 psi)

23°C (72°F)

30-35°C (85-95°F)

Below 30%

179-254 kPa (26-37 psi)

1336-1667 kPa (194-242 psi)

20°C (68°F)

30-50%

192-268 kPa (28-39 psi)

1378-1708 kPa (200-248 psi)

22°C (70°F)

Above 50%

213-296 kPa (31-43 psi)

1440-1770 kPa (209-256 psi)

24°C (75°F)

36-41°C (95-105°F)

Below 20%

199-268 kPa (29-39 psi)

1550-1867 kPa (225-271 psi)

23°C (73°F)

20-40%

206-282 kPa (30-41 psi)

1570-1887 kPa (228-274 psi)

24°C (75°F)

Above 40%

220-296 kPa (32-43 psi)

1612-1908 kPa (234-277 psi)

25°C (77°F)

42-46°C (105-115°F)

Below 20%

220-289 kPa (32-42 psi)

1777-2053 kPa (258-298 psi)

25°C (77°F)

Above 20%

227-296 kPa (33-43 psi)

1791-2060 kPa (260-299 psi)

27°C (79°F)

47-49°C (115-120°F)

Below 30%

248-310 kPa (36-45 psi)

1970-2218 kPa (286-322 psi)

28°C (82°F)

Air Conditioning (A/C) System Performance Test L26

Table 1: A/C Performance Table

Test Description

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

    • The current ambient air temperature (AAT)
    • The current relative humidity
    • The high side pressure of the A/C system
    • The low side pressure of the A/C 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 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 (AATs).

Step

Action

Values

Yes

No

Important: 

   • The ambient air temperature (AAT) must be at least 16°C (60°F).
   • 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 for about 2 minutes.
  4. Turn OFF the ignition.
  5. Install the J 43600 ACR 2000 Air Conditioning Service Center.
  6. Record the ambient air temperature (AAT) 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 AAT AT THE TIME OF THE TEST.

  1. Close the vehicle doors and windows.
  2. Open the driver door window 12.7-15.2 cm (5-6 in).
  3. Select the following HVAC control setting:
  4. • The A/C is ON.
    • The coldest temperature setting
    • The maximum blower speed
    • Recirculation mode
    • The instrument panel (I/P) outlet mode
    • All I/P outlets are OPEN
  5. Install the temperature probes of the J 43600 in the left and right center panel air outlets.
  6. Apply the parking brake.
  7. Place the transmission in PARK.
  8. Start the engine.
  9. Operate the A/C system for 5 minutes.
  10. Inspect A/C components for the following conditions:
  11. •  Abnormal frost areas
    • Unusual noises

    Important: When performing this step it is necessary to press the RESET button on the J 43600 before pressing the PRINT button.

  12. Print the following information:
  13. • The panel outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  14. Compare the low and high side pressures and the panel output temperatures to the A/C performance table below.

Does all the data recorded fall within the specified ranges of the A/C performance table?

--

Go to Step 8

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 panel output temperature to the A/C performance table.

Does all the data recorded fall within the specified ranges of the A/C performance table?

--

Go to Step 8

Go to Step 4

4

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

--

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

Go to Step 5

5

Is the low side pressure greater than the specified range, but the high side pressure is within or less 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 greater than the specified ranges?

--

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

Go to Step 7

7

Is the high side pressure greater than the specified range, but the low side pressure is within or less 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 or to Symptoms - HVAC Systems - Automatic

A/C System Pressure - Zone Classification

A/C System Pressure - Zone Classification


Object Number: 1538564  Size: MF

A/C Performance Table

Ambient Air Temperature

Relative Humidity

Service Port Pressure

Maximum Left Center Discharge Air Temperature

Low Side

High Side

13-18°C (55-65°F)

0-100%

151-179 kPa (22-26 psi)

868-1267 kPa (126-184 psi)

8°C (46°F)

19-24°C (65-75°F)

Below 40%

151-186 kPa (22-27 psi)

888-1281 kPa (129-186 psi)

8°C (46°F)

Above 40%

151-206 kPa (22-30 psi)

1019-1419 kPa (148-206 psi)

10°C (50°F)

25-29°C (76-85°F)

Below 35%

151-192 kPa (22-28 psi)

1109-1412 kPa (161-205 psi)

8°C (46°F)

35-50%

151-199 kPa (22-29 psi)

1178-1460 kPa (171-212 psi)

10°C (50°F)

Above 50%

151-220 kPa (22-32 psi)

1240-1550 kPa (180-225 psi)

13°C (54°F)

30-35°C (85-95°F)

Below 30%

151-206 kPa (22-30 psi)

1267-1591 kPa (184-231 psi)

10°C (50°F)

30-50%

151-220 kPa (22-32 psi)

1322-1639 kPa (192-238 psi)

13°C (54°F)

Above 50%

165-241 kPa (24-35 psi)

1378-1708 kPa (200-248 psi)

14°C (57°F)

36-41°C (95-105°F)

Below 20%

151-213 kPa (22-31 psi)

1460-1756 kPa (212-255 psi)

12°C (52°F)

20-40%

158-227 kPa (23-33 psi)

1481-1791 kPa (215-260 psi)

13°C (55°F)

Above 40%

172-241 kPa (25-35 psi)

1529-1832 kPa (222-266 psi)

14°C (57°F)

42-46°C (105-115°F)

Below 20%

172-227 kPa (25-33 psi)

1660-1922 kPa (241-279 psi)

13°C (54°F)

Above 20%

179-241 kPa (26-35 psi)

1681-1942 kPa (244-282 psi)

14°C (57°F)

47-49°C (115-120°F)

Below 30%

186-248 kPa (27-36 psi)

1839-2087 kPa (267-303 psi)

15°C (59°F)