A/C Signal: Description and Operation

Description
When the A/C is requested the Powertrain Control Module provides a ground path through A/C compressor relay circuit. When the A/C compressor relay control circuit is grounded the A/C compressor clutch relay is then energized. After the A/C request has been selected the PCM will delay grounding the A/C compressor relay control circuit for 0.3 second. This allows the PCM to adjust the engine idle RPM for the additional load.
The PCM will temporarily de-energize the A/C compressor clutch relay for one or more of the following conditions:
- A hot engine restart.
- A wide Open Throttle.
- Engine Speed is greater than 6000 RPM.
- An Idle Air Control valve reset.

The A/C compressor clutch relay will remain de-energized when one or both of the following conditions exist:
- A DTC P0530 is set.
- There is no A/C request signal due to an open A/C select switch circuitry.