Cooling System: Description and Operation

Fan Operating Mode:

The engine control module controls the power transistors (high speed and low speed) in the module to provide radiator fan motor and condenser fan motor rotation controls in accordance with the engine coolant temperature and vehicle speed.
1. Radiator Fan (Low Speed Rotation)
- When the engine control module turns on the power transistor (low speed) in the module, the current flows from the ignition switch to the engine control module through the radiator fan motor relay (LO) coil.If the current flows to the fan motor relay coil, the switch of the relay turns on to supply the motor driving power (for low speed rotation). This will cause the current to flow from the battery to the ground through the radiator fan motor, relay switch and resistor, rotating the radiator fan at low speeds.

2. Condenser Fan (Low Speed Rotation)
- The power from the A/C compressor lock controller turns on the condenser fan motor relay (LO) to rotate the condenser fan at low speeds.

3. Radiator Fan, Condenser Fan (High Speed Rotation)
- When the engine control module turns on the power transistor (high speed) in the module. the radiator fan motor relay (HI) and condenser fan motor relay (HI) will operate and the motor driving power (for high speed rotation) is sent to the radiator fan motor and condenser fan motor to rotate the radiator fan and condenser fan at high speeds.

NOTE: In the event of faulty water temperature sensor, the engine control module commands the fan motors (for both radiator and condenser) to rotate at high speeds.