Test Description

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

1. 2. The A/C compressor relay output is disabled if engine coolant temperature is above 121°C (250°F).
2. 3. Placing the mode switch in any position other than OFF, along with placing the air temperature control switch in a cold setting, activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, bi-level mode is used for consistent testing.
3. 5. The HVAC control assembly in inoperative when the module does not respond to any operator controls requests.
4. 8. The scan tool checks the function of the A/C low pressure switch through the A/C compressor cycling data.
   Fig 1: HVAC Compressor Clutch Does Not Engage (1 Of 5)

   Courtesy of GENERAL MOTORS CORP.
   Fig 2: HVAC Compressor Clutch Does Not Engage (2 Of 5)

   Courtesy of GENERAL MOTORS CORP.
   Fig 3: HVAC Compressor Clutch Does Not Engage (3 Of 5)

   Courtesy of GENERAL MOTORS CORP.
   Fig 4: HVAC Compressor Clutch Does Not Engage (4 Of 5)

   Courtesy of GENERAL MOTORS CORP.

Fig 5: HVAC Compressor Clutch Does Not Engage (5 Of 5)

Courtesy of GENERAL MOTORS CORP.