A/c Request Signal Cadillac DeVille Concours

The air conditioner mode selector is mounted on instrument panel. This mode selector provides a simple "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. To check function of the A/C mode selector, perform functional check of A/C mode selector. See SYSTEM/COMPONENT TESTS article.