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 |
| • | The A/C compressor clutch |
When the heater and A/C control is placed in the A/C mode, a request
signal is sent to the PCM. The PCM then energizes the A/C clutch relay. The
PCM also turns the cooling fans ON when A/C is requested. The
A/C clutch relay is controlled by the PCM so that the PCM can increase
idle speed before turning ON the A/C compressor clutch or disable
the A/C compressor clutch during WOT, or high coolant temperature.
The PCM energizes the A/C clutch whenever the engine is
running less than 3,950 RPM and A/C has been requested. The PCM will
not energize the A/C clutch whenever any of the following conditions are
present:
| • | Throttle angle more than 86 percent |
| • | Ignition voltage less than 10 volts |
| • | Engine speed more than 4294 RPM |
| • | ECT more than 125°C (257°F) -- The PCM
re-enables the A/C at 121°C (250°F). |
The scan tool is used in diagnosing the A/C system. The PCM has the
ability to display the following parameters:
| • | A/C request input to the PCM |
| • | A/C clutch ON or OFF status |
