Air Conditioning Switch: Description and Operation

A/C SELECT SIGNAL


PURPOSE

This signal informs the Powertrain Control Module (PCM) that the air conditioning has been selected.


OPERATION

When the A/C switch is activated by the driver, and the A/C low pressure switch is closed, a signal is sent to the PCM. If the PCM receives this signal as well as the A/C request input, the PCM will energize the A/C clutch relay allowing clutch to engage.

The PCM also sends output signals to the Automatic Idle Speed (AIS) motor to raise the idle speed to a predetermined rpm to compensate for the additional load placed upon the engine.

If the A/C low pressure switch opens, indicating low Freon level, the PCM will not receive the signal. If the signal is not received, the PCM will de-energize the A/C relay.