A/C "On" Switch

The air conditioner "on" switch is mounted in instrument panel. This switch provides a simple "on" or "A/C request" signal which is monitored by the ECM. The ECM uses this signal to determine control of the A/C clutch relay (if equipped) and to adjust idle speed when A/C compressor clutch is engaged. On some models, ECM may 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 I - SYS/COMP TESTS article in this section.