VCM, Input

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

CONSTRUCTION
The VCM controlled A/C circuit system consists of:
- Heater and A/C control assembly located at the dashboard.
- Two A/C pressure switches (LOW and HIGH).
- A/C relay.
- Compressor clutch.

OPERATION
Turning "ON" air conditioning supplies battery voltage to the VCM on CKT 66. If there is sufficient pressure in the A/C system and/or the ambient temperature is not too cold, the A/C pressure switch will close and supply voltage to the switch side of the A/C relay on CKT 248. After a calibrated delay time (approximately 20 seconds), the VCM will ground CKT 259, enabling the relay and applying voltage to CKT 901. The normally closed A/C high pressure cutoff switch will provide voltage to CKT 59 and enable the A/C clutch. Voltage is also supplied to the VCM on CKT 59. This voltage signal allows the VCM to make idle, timing and fuel corrections for smoother clutch engagements.