GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Express 🢒 HVAC 🢒 HVAC Systems - Manual 🢒 HVAC Compressor Controls System Check

Step

Action

Normal Result(s)

Abnormal Result(s)*

1
  1. Start the engine.
  2. Place the blower motor switch in the HI position.
  3. Place the mode switch in the MAX A/C position.
    • The blower motor operates.
    • The A/C compressor clutch engages.
  1. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 4.3L
  2. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 5.0L, 5.7L
  3. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 7.4L

If no DTC's are stored, or for the 6.5L engine,use:

HVAC Compressor Clutch Does Not Engage .

2
  1. Place the mode switch in the OFF position.
  2. Place the blower motor switch in the OFF position.
    • The blower motor will cease to operate.
    • The A/C compressor clutch will disengage.
  1. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 4.3L
  2. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 5.0L, 5.7L
  3. Air Conditioning (A/C) Compressor Control Circuit Diagnosis in Engine Controls 7.4L

If no DTC's are stored, or for the 6.5L engine,use:

HVAC Compressor Clutch Does Not Disengage .

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.