Radiator Cooling Fan Control Module: Description and Operation

With the Ignition Switch in the RUN position, the Cooling Fan operates when any of the following conditions occur; 1) Cooling Fan Temperature Switch closes; (2) The A/C is turned on; (3) The ECA supplies a ground for the Cooling Fan Relay.

Cooling Fan Temperature Switch

The Cooling Fan Temperature Switch monitors the engine coolant temperature in the radiator. Once the engine coolant temperature rises above 97~C (206~F), the Radiator Temperature Switch closes. Current flows through the ENGINE fuse and Cooling Fan Relay # 1 to ground. As a result, the Cooling Fan Relay contacts close, current flows through the COOLING FAN fuse to the Cooling Fan Motor, and the fan operates.

In vehicle with automatic transaxles, there is a cooling Fan Temperature Switch that monitors the engine coolant temperature at the intake manifold. Once the engine coolant temperature at the intake manifold rises above 108~C (226~F), the Cooling Fan Relay # 2 to ground. As a result, the Fan Relay contacts close, current flows from the COOLING FAN fuse to the Cooling Fan Motor, and the fan operates.

ECA

The ECA monitors the coolant temperature, vehicle speed, and A/C status to determine when the Cooling Fan will operates. The ECA supplies a ground to the Cooling Fan Relay which closes its contacts and runs the Cooling Fan when necessary.

In LX vehicles, the Cooling Fan is controlled by the Integrated Relay Control Module (IRCM). The EEC Module receives input from the coolant temperature switches and the A/C system and then sends signals to the Electro-Drive Fan (EDF) Relay or the high-speed Electro-Drive (HEDF) Relay (located in the Integrated Relay Control Module) to control the operation of the Cooling Fan.