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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1098 (Heating, Ventilation, And Air Conditioning) >> Diagnostic Information and Procedures >> Air Conditioning (A/C) System Performance Test >> Test Description

Test Description

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.

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

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

  1. 1:  This step determines if the A/C system has at least the minimum refrigerant charge required to operate the system without damage.
  2. 2:  This step measures the performance of the A/C system.
  3. 3:  This step is to allow for vehicle variations as well as high ambient temperatures.
Step Action Values Yes No
IMPORTANT:
  • The ambient air temperature 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 before starting 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 5 minutes.
  4. Turn OFF the ignition.
  5. Install the J 43600  ACR 2000 Air Conditioning Service Center. See Special Tools .
  6. Record the ambient air temperature displayed on the J 43600  . See Special Tools .
  7. Record the low and high side STATIC pressure readings.
Are both the low side and high side pressures above the specified value?		 More than 16°C (60°F) - 345 kPa (50 psi)
More than 24°C (75°F) - 483 kPa (70 psi)
More than 33°C (90°F) - 690 kPa (100 psi)		 Go to Step 2  Go to Leak Testing 
2 
IMPORTANT:
  • If DTC B0157 is set, the compressor clutch will not engage until it is cleared.
  • 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 drivers door window 5-6 inches (12.7-15.24 cm).
  3. Start the engine.
  4. With a scan tool clear any DTCs stored in the HVAC module.
  5. Select the following HVAC control settings:
    • The A/C is ON
    • The maximum blower speed
    • The Face mode
    • The coldest temperature setting
    • Passenger setting is off
    • All A/C outlets are OPEN
  6. Install the temperature probes of the J 43600  in the left and right center A/C air outlets. See Special Tools .
  7. Apply the parking brake.
  8. Place the transaxle/transmission in one of the following positions:
    • PARK, Automatic
    • NEUTRAL, Manual
  9. Operate the A/C system for 5 minutes.
  10. Inspect A/C components for the following conditions:
    • Abnormal frost areas
    • Unusual noises
    11. IMPORTANT: Make sure that the compressor is engaged when taking the data.
    Press the RESET button, before using the print function of the J 43600  . See Special Tools .
  11. Print the following information:
    • The outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  12. Compare the low and high side pressures and the output temperatures 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 3 
3  If the pressures and temperatures recorded do not fall within the specified ranges of the A/C Performance Table:
  1. Continue to operate the A/C system for an additional 5 minutes.
  2. RESET the J 43600  and record the pressures and temperatures again. See Special Tools .
  3. Compare the low and high side pressures and the output temperature to the A/C Performance Table.

Does all the data recorded fall within the specified ranges?		 - Go to Step 8  Go to Step 4 
4 See the A/C system Pressure - Zone Classification chart.
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 greater than the specified range, but the high side pressure 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 or within the specified range, but the low side pressure is 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 - Automatic
Fig 1: A/C System Pressure - Zone Classification
GM1993685Courtesy of GENERAL MOTORS CORP.
A/C Performance Table (LY7, LP1)

Ambient Air Temperature Relative Humidity Service Port Pressure Maximum Left Center Discharge Air Temperature Maximum Left Rear Discharge Air Temperature
Low Side Service Port Pressure High Side Service Port Pressure
13-18°C (55-65°F) 0-100% 151-337 kPa (22-49 psi) 771-1150 kPa (112-167 psi) 9°C (48°F) 10°C (50°F)
19-24°C (66-75°F) Below 40% 151-234 kPa (22-34 psi) 737-1102 kPa (107-160 psi) 9°C (48°F) 12°C (52°F)
Above 40% 165-254 kPa (24-37 psi) 881-1191 kPa (128-173 psi) 12°C (52°F) 13°C (55°F)
25-29°C (76-85°F) Below 35% 165-254 kPa (24-37 psi) 826-1212 kPa (120-176 psi) 12°C (52°F) 13°C (55°F)
35-50% 192-261 kPa (28-38 psi) 875-1219 kPa (127-177 psi) 13°C (54°F) 14°C (57°F)
Above 50% 179-275 kPa (26-40 psi) 909-1233 kPa (132-179 psi) 13°C (55°F) 15°C (59°F)
30-35°C (86-95°F) Below 30% 179-282 kPa (26-41 psi) 1047-1371 kPa (152-199 psi) 14°C (57°F) 17°C (61°F)
30-50% 213-289 kPa (31-42 psi) 1129-1329 kPa (164-193 psi) 15°C (59°F) 18°C (63°F)
Above 50% 220-303 kPa (32-44 psi) 1136-1281 kPa (165-186 psi) 15°C (59°F) 18°C (63°F)
36-41°C (96-105°F) Below 20% 241-316 kPa (35-46 psi) 1329-1570 kPa (193-228 psi) 18°C (64°F) 19°C (66°F)
20-40% 241-316 kPa (35-46 psi) 1309-1488 kPa (190-216 psi) 19°C (65°F) 19°C (66°F)
Above 40% 248-323 kPa (36-47 psi) 1267-1412 kPa (184-205 psi) 19°C (66°F) 19°C (66°F)
42-46°C (106-115°F) Below 20% 275-344 kPa (40-50 psi) 1543-1729 kPa (224-251 psi) 19°C (66°F) 23°C (72°F)
Above 20% 275-344 kPa (40-50 psi) 1488-1743 kPa (216-253 psi) 22°C (70°F) 23°C (72°F)
47-49°C (116-120°F) Below 30% 303-372 kPa (44-54 psi) 1646-1963 kPa (239-285 psi) 23°C (72°F) 23°C (73°F)
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