Air Conditioning Switch: Description and Operation

PURPOSE
Signals the powertrain control module engine (PCME) when A/C is running. PCME detects this condition and increases idle speed control valve duty cycle signal (more "ON" time vs. "OFF" time).

OPERATION
When it receives the A/C signal, the PCME increases idle speed to compensate for the additional A/C compressor load and helps to insure efficient A/C operation during engine idling.