PCM Controlled A/C Circuit Diagnosis

Diagnostic Chart:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses the A/C relay to control the A/C compressor. With an A/C mode selected, the HVAC module sends a Glass 2 message to the PCM. When the PCM receives the message, the PCM turns ON the A/C relay coil by grounding the A/C relay control circuit. This closes the relay contacts, and applies a fused battery voltage to the A/C compressor clutch coil. The PCM enables the compressor clutch whenever following conditions are present:
^ Engine is running.
^ The PCM has received the A/C Request.
^ TP sensor indicates a throttle angle below 90 percent.
^ System voltage greater than 8 volts.
^ Engine speed is greater than 500 RPM.

DIAGNOSTIC AIDS
If the condition is intermittent, refer to Intermittent Conditions in Symptoms. Intermittent Conditions