A/C Signal: Description and 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. 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.