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 5,000 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 more than 45 psi. |
| • | The A/C high pressure cutout switch pressure is more than 420 psi. |
| • | The engine speed is more than 5,500 RPM. |
| • | ECT is more than 121°C (250°F). |
Any of the conditions described above inhibits the A/C compressor relay
operation.
