A/C Request Signal
WARNING: This page is about a different car, the 2003 Saturn LW200 and 2003 Saturn L200. However, it is still accessible from the selected car via links, so may be relevant.
The air conditioner mode selector is mounted on instrument panel. This mode selector provides a simple "on" (A/C request) signal which is monitored by the PCM. PCM uses this signal to determine control of A/C clutch relay (if equipped) and to adjust idle speed when A/C compressor clutch is engaged. On some models, PCM may also activate electric 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.