Cooling System: Description and Operation

Voltage is present at the contacts of the High Speed Cooling Fan Relay at all times through the CO0LING FAN Fuse. With the Ignition Switch in "START" or "RUN", voltage is present at the coils of the Low Speed Cooling Fan Relay and the High Speed Cooling Fan Relay through the ENGINE Fuse. With the High Speed Cooling Fan Relay de-energized, voltage is also present at the contacts of the Low Speed Cooling Fan Relay.

When the Powertrain Control Module (PCM) determines that the engine coolant temperature is above 97°C (207°F), it grounds circuit 197 (BL/O) with 2.0L or 174 (R/W) with 2.5L to Low Speed Cooling Fan Relay. The Relay contacts close and power flows through the CO0LING FAN Fuse, High Speed Cooling Fan Relay (de-energized), Low Speed Cooling Fan Relay and the low speed winding of the Cooling Fan Motor to ground. The Fan runs at low speed.

The Fan will run at low speed until:
a. the Low Speed Cooling Fan Relay coil is no longer grounded and the Fan shuts off, or
b. engine coolant temperature reaches 108°C (226°F).

If the PCM senses coolant temperature above 108°C (226°F), it grounds the coil of the High Speed Cooling Fan Relay, energizing the Relay and switching current flow from the Low Speed Cooling Fan Relay contacts to the high speed winding of the Cooling Fan Motor; the Fan runs at high speed. On vehicles equipped with a 2.5L engine and air conditioning, the Condenser Fan Relay coil is grounded whenever the air conditioning system is activated, and the Cooling Fan Motor runs continuously at Hi speed.