Compressor Clutch Relay: Description and Operation

Voltage is provided at all times to the heater control panel through fuse 13, and to the A/C compressor clutch relay contacts through fuse 58. With the ignition switch ON (II), voltage is supplied to the control panel and the relay coil through fuse 3 (in the driver's under-dash fuse/relay box). The control panel is grounded at G401.

When you push the A/C button ON with the ignition switch ON (II) and the heater fan switch not in the OFF position, the control panel will ground the A/C ON input of the PCM or ECM through the A/C pressure switch. The PCM or ECM then grounds the A/C compressor clutch relay coil. This energizes the coil, which closes the relay contacts and provides voltage through fuse 58 to the A/C compressor clutch. The clutch then engages and begins turning the compressor.