OEM Circuit Diagrams: Fans: A/Con

The ECM/PCM detects that the A/C is ON through an input from the A/C Pressure Sensor. Upon receiving the A/C ON information, the ECM/PCM provides ground to the coil of the Radiator Fan Relay, energizing it. Battery voltage is supplied to the A/C Condenser Fan Motor and Radiator Fan Motor in series through the energized relay, which activates the motors at low speed.

If the refrigerant pressure rises above 1520 kPa (221 psi), the A/C Pressure Sensor signals the ECM/PCM to run the fans at high speed. The ECM/PCM provides ground to the coils of the A/C Condenser Fan Relay, the Radiator Fan Relay, and the Fan Control Relay, energizing them. Battery voltage is supplied to the A/C Condenser Fan Motor and Radiator Fan Motor through their respective energized relays, which activates the motors at high speed.