DTC 66

DTC 66 - Low A/C Refrigerant Charge:

A/C Clutch Control Wiring Circuit:

Circuit Description:

The PCM monitors the A/C request signal (CKT 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 DTC 66. With a current DTC 66 stored, the PCM will not allow the compressor to be turned "ON" until the next ignition cycle. If DTC 66 is set during three ignition cycles, the A/C clutch will be disabled until the DTC 66 is cleared from memory.

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

DTC 66 does not illuminate the MIL (Service Engine Soon).

Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.
Check for:
^ Poor Connection or Damaged Harness - Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.