Radiator Cooling Fan Motor: Description and Operation

COOLING SYSTEM SERVICE

The electric drive cooling fan system consists of a fan and a two-speed electric motor. This fan motor will only run when the ignition switch is in the run position. The cooling fan is controlled during engine operation by the integrated relay control module (IRCM) and the EEC-IV module. These controls cause the fan to run at low speed when the engine temperature reaches approximately 215°F, or when the A/C is on and vehicle does not provide enough air flow. The fan will continue to run until engine temperature drops to approximately 210°F. The cooling fan will run at high speed when fan has been operating at low speed, but engine temperature is still above 230°F, or during idle when engine temperature has reached approximately 236°F. The cooling fan will begin to operate at low speed when engine temperature drops to approximately 224°F. The cooling fan does not cycle with A/C.

DESCRIPTION

The cooling system includes a radiator, circulating pump, and a cooling fan which is activated by the integrated relay control module. Also included in the keeping the cooling system is a separate coolant recovery reservoir which is located beside the radiator and aids in maintaining the correct volume of coolant. The water pump is a conventional design and is driven by the accessory drive belt. A thermostat is in a water outlet connection housing at one end of the engine. The thermostat ensures rapid engine warm-up by restricting coolant flow at lower operating temperatures. It also assists in keeping the engine operating temperature within predetermined limits. The coolant normally contains a 50/50 mix of water and permanent coolant/antifreeze fluid such as Ford Cooling System Fluid E2FZ-1 9549-A (ESEM97B44-A) or equivalent. The addition of more water than recommended will raise the freezing protection temperature and weaken the corrosion inhibitors. Refer to Specifications for the cooling system capacity for all vehicles.

NOTE: The system must be maintained with the correct concentration and type of antifreeze to prevent corrosion damage.

The electric radiator cooling fan motor is mounted within a shroud behind the radiator. The integrated relay control module actuates the fan when the coolant reaches a specified temperature, and/or when the engine reaches a specified speed, and/or when the air conditioning clutch is activated, if so equipped.

WARNING: THE ENGINE ELECTRIC COOLING FAN MAY COME ON AT ANY TIME WITHOUT WARNING, EVEN IF THE ENGINE IS NOT RUNNING.

OPERATION

When the coolant is cold, the thermostat is in the closed position and the coolant flow is restricted to the cylinder block, head, intake manifold and heater. As the temperature increases, the thermostat opens, allowing a portion of the coolant to pass into the radiator. The coolant flows through the radiator tubes and is cooled by air passing over the cooling fins assisted by the cooling fan. Coolant is then circulated from the radiator outlet tank through the water pump and into the cylinder block to complete the circuit. The coolant expands as the temperature and pressure rise in the system. When the limiting system working pressure is reached, the pressure relief valve in the radiator filler cap is lifted from its seat and allows coolant to flow through the radiator filler neck and the overflow hose into the coolant recovery reservoir. The radiator filler cap has a rubber seal on the underside to prevent leakage. When the system temperature and pressure drop, the coolant contracts in volume and the pressure in the radiator is reduced. The coolant in the reservoir bottle will then flow back into the radiator through the vacuum relief valve in the radiator filler cap. The integrated relay control module activates the cooling fan motor when the coolant reaches a specified temperature, and/or when the engine reaches a specified temperature. On vehicles equipped with air conditioning, the cooling fan motor is activated whenever the air conditioning clutch is engaged. Refer to electro-drive cooling fan service procedures.