Chart 1 No Compressor Operation

Diagnostic Chart:

Electrical Diagram:

CIRCUIT DESCRIPTION

The compressor clutch coil is fed power through the A/C relay and is grounded through the A/C ground CKT 150. Both cooling fans and the hydraulic brake modulator share this ground (G105) from splice (S106) to ground.

For the compressor clutch to cycle, the outside air temperature must be above 40°F (4°C). If the coolant temperature is above 126°C (259°F) the Body Control Module (BCM) will disengage the clutch to prevent an engine overheat condition.

A faulty power steering switch can trigger the PCM to disable the clutch.

TEST DESCRIPTION

Test numbers refer to circled numbers on the diagnostic chart.

1. This step checks the PCM output for the A/C clutch relay control.

2. This step looks at the sensor values seen by the BCM and PCM to determine if a sensor is not allowing the compressor clutch request.

3. This branch decides between a faulty relay or circuitry problem.

4. This branch determines if fault is in power source, circuitry, or clutch itself.