Fan Control Circuit

The PCM monitors certain engine functions (ECT sensor, vehicle speed, A/C demand, A/C head pressure, etc.) to determine fan control needs. The PCM will send the desi red fan speed to the VCRM through the data link connector (DLC). The VCRM then adjusts the fan speed and outputs the appropriate voltage to the fan control (from approximately 6 volts to 12 volts depending upon battery state of charge) through the fan control output driver with a pulse width modulated duty cycle. If the engine temperature exceeds the normal operating limit, the fan control speed modulates to try to reduce temperature and the A/C is shut oft. If the vehicle speed exceeds 47mph, the fan control will be shut off.