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A/C On (A/C Request) Signal

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The air conditioner "on" switch is mounted in instrument panel. This switch provides a simple "on"("A/C request") signal, which is monitored by PCM. The PCM uses this signal to determine control of the A/C clutch relay (if equipped) and to adjust idle speed when air conditioner compressor clutch is engaged. On "U" model Vans, PCM also activate radiator cooling fan when this signal is present. If this signal is not present on A/C equipped vehicles, vehicle may idle rough when A/C compressor cycles. To check function of the A/C switch, perform functional check of switch. See appropriate SYSTEM/COMPONENT TESTS - GASOLINE article in the ENGINE PERFORMANCE section.

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