A/C Signal: Description and Operation

A/C Clutch Control - S/T - 92 2.5A/2.8R - 93 2.5A:

PURPOSE
Provides ECM control of the A/C clutch to improve idle quality and engine performance.

CONSTRUCTION
The ECM controlled A/C circuit system consists of:
- Heater and A/C control assembly located at the dashboard.
- A/C pressure cycling switch.
- Control relay
- Compressor clutch.

OPERATION
The A/C control relay is controlled by the ECM. This allows the ECM to:
- Delay clutch engagement until idle speed is increased.
- Release clutch when idle speed is to low.
- Smooths cycling of the compressor by providing additional fuel at the instant clutch is applied.

Turning "ON" air conditioning supplies battery voltage to the the clutch control relay and terminal "B8". After a time delay of about 1/2 second the ECM will ground terminal "A4" and close the control relay. A/C compressor clutch will then engage.