In order to improve engine operation, and protect the A/C
compressor and A/C clutch during Wide Open Throttle (WOT) performance, the
A/C compressor operation is controlled by the PCM.
This A/C system consists of the following components:
| • | The heater and A/C control module |
| • | The A/C high pressure cut-out switch |
| • | The A/C compressor cycling switch |
| • | The A/C compressor clutch relay |
| • | The A/C compressor clutch |
When the heater and A/C control module is placed in an A/C mode, a request
signal is sent to the PCM. The PCM will then energize the A/C clutch relay,
unless abnormally high or low A/C pressure is detected. The A/C clutch
relay is controlled by the PCM so that the PCM can increase idle speed
before turning ON the clutch or disable the clutch during WOT, or high
coolant temperature.
The PCM energizes the A/C clutch whenever the engine is
running less than 5000 RPM and the A/C has been requested, unless any
of the following conditions are met:
| • | Wide Open Throttle (WOT). |
| • | The A/C compressor cycling switch pressure is less than 18 psi
or greater than 45 psi. |
| • | The A/C high pressure cutout switch pressure is greater than 420 psi. |
| • | The engine speed is greater than 5500 RPM. |
| • | ECT is greater than 121°C (250°F). |
Any of the conditions described above inhibits the A/C compressor relay
operation.
