Operation CHARM: Car repair manuals for everyone.

A/C Request

Purpose:
This signal notifies the PCM that the operator of the vehicle has requested that the A/C system be turned On. If engines conditions allow, the PCM will energize the A/C coil relay by supplying a ground.

Operation:
The A/C request input is received from the A/C control head. When the A/C is turned On, a B+ signal from the A/C switch, located in the A/C control head, is sent to the PCM. If the A/C low- and high-pressure switches are closed then the B+ signal is received by the PCM.