Chart C-10, A/C Compressor Clutch Control

With A/C on, alternator voltage is supplied to A/C power relay. This actuates the A/C power relay, through the low- and high-pressure switches, to A/C clutch control relay.

If the system refrigerant level is okay, low-pressure switch will be closed, completing circuit through high-pressure cut-off switch to circuit No. 257.

Circuit No. 257 supplies voltage to A/C control relay and ECM terminal B8. The ECM will wait about 1/2 second then ground terminal A4 and circuit No. 248. This will close the A/C relay, allowing current to flow through the relay and circuit No. 340 to engage compressor clutch.

Fig 1: Chart C-10 Flow Chart, A/C Clutch Control

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart C-10 Schematic, A/C Clutch Control

Courtesy of GENERAL MOTORS CORP.