Idle Speed Control
WARNING: This page is about a different car, the 1995 Cadillac Seville, 1995 Cadillac Eldorado, and 1995 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
The PCM can modify engine idle during A/C operation to minimize the effects of compressor operation on vehicle idle. When the PCM receives a clutch engagement signal from the ACP, the PCM adjusts the idle speed control motor in anticipation of increased engine load.