General Description
The A/C compressor clutch is controlled by the powertrain control module
(PCM). This allows the PCM to manage idle quality, improve wide open throttle
performance, and to protect the A/C system from excessively high and
low pressures.
The PCM controlled air conditioning system uses a variable displacement
compressor referred to as a V-5 compressor. The V-5 compressor meets the A/C
requirements without cycling. For a description of the system and an
explanation of the components used, refer to
Air Conditioning (A/C) System Description
in Heating, Ventilation, and Air Conditioning.
System Operation
The PCM controlled air conditioning system consists of an A/C compressor
clutch relay, an A/C compressor clutch and an A/C refrigerant pressure sensor.
The PCM receives an A/C request signal from the A/C selector switch.
When A/C is requested, the powertrain control module (PCM) provides a ground
path to the A/C clutch relay control circuit. When the relay circuit is
grounded, the A/C compressor clutch relay is energized. The PCM delays
grounding the relay circuit for 0.3 second, so the PCM can 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 wide open throttle (TP sensor over 90 percent). |
| • | Engine RPM more than 6000 RPM. |
| • | During an idle air control (IAC) valve reset. |
| | The A/C compressor clutch relay will remain de-energized when one or
both of the following conditions exist: |
| • | There is no A/C request signal to the PCM. |
| | Refer to
Refrigerant System Checks
in
Heating, Ventilation, and Air Conditioning for more information on the A/C
refrigerant systems. |
