A/C Fan No. 1 Relay

The A/C fan no. 1 and no. 2 relays are responsible for cycling the main and auxiliary fan motors between series and parallel operation. The A/C fan no. 1 and no. 2 relays share the same power feed from the ECU-IG fuse and share the same ground path through the A/C refrigerant pressure switch and the Powertrain Control Module (PCM). When the engine is running and the Engine Coolant Temperature (ECT) is below 83°C (181°F), the PCM provides a ground energizing both the fan no. 1 and no. 2 relays. With both relays energized an open circuit condition exists for each fan motor and neither fan motor runs. When the ECT reaches 93°C (199°F), the PCM removes the ground and both relays are de-energized. With the fan no. 1 relay de-energized voltage is supplied to the main fan motor. With the fan no. 2 relay de-energized ground is supplied to the auxiliary fan motor. Both fan motors will now run at full speed.