Manual A/C System

A/C Control Circuit Diagram:

Code 66 Diagnostic Chart:

CIRCUIT DESCRIPTION:
The PCM monitors the A/C request signal circuit 67 and completes the ground for the A/C relay when an A/C mode is selected at the control head and refrigerant pressure is sufficient to close the A/C pressure cycling switch. If the refrigerant pressure is low and the A/C request signal causes the PCM to cycle the compressor too often, the PCM protects the compressor by disabling the A/C relay and storing a Code 66. The PCM will not allow the compressor clutch to be turned "ON" until the next ignition cycle. If a Code 66 is set during three ignition cycles, then the A/C clutch will be disabled until the Code 66 is cleared from the memory. Code 66 does not illuminate the "SERVICE ENGINE SOON" light.

Code 66 will set if the A/C compressor cycles "ON" 10 or more times within 15 minutes, and the compressor "ON" time for each cycle is less than 1.5 seconds.

DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, worn through wire insulation, or a wire broken inside the insulation.

^ Poor connection or damaged harness. Inspect harness connectors for backed out terminals, improper mating, broken locks, bad terminals, poor terminal to wire connections, and damaged harness.