A/C Idle-Up Circuit (PRIZM)

A/C compressor control module sends an idle-up signal to PCM when A/C compressor clutch is in operation. PCM compensates for extra engine load by adjusting engine idle speed through IAC valve. See IDLE AIR CONTROL VALVE (PRIZM) . PCM then sends A/C compressor control module an A/C cut-out signal to cut operation of A/C compressor clutch. A/C compressor control module will then resume normal cycling of A/C compressor clutch when engine returns to a lighter load. A malfunction in A/C idle-up circuit can set DTC P0505. For test procedure with DTC set, see appropriate SELF-DIAGNOSTICS article.