Electric Cooling Fan Does Not Operate

ELECTRIC COOLING FAN DOES NOT OPERATE

TYPES OF FAILURES
Bad Fan Control Circuits- The fan control circuits fail to energize the cooling fan when necessary. This may be the fault of either the coolant temperature switch or the cooling fan relay.

Power/Ground Circuit - A blown fuse or broken/shorted wire is preventing the fan from operating. A poor ground connection may reduce the performance of the cooling fan.

Bad Fan Motor - The fan motor fails to operate when both power and ground are applied. If this is suspected, always verify that an object has not become wedged between the fan blades and shroud, and is preventing the fan from rotating.

CAUTION: When checking the fan blades for free travel and spin, always disconnect the negative battery terminal to prevent personal injury.

SYMPTOMS
- Engine overheats at idle or low driving speeds.
- Engine does not overheat at cruising or highway speeds.

NOTE: With speeds in excess of 25 mph, sufficient air flow is forced across the radiator to cool the engine without the use of the cooling fan (under normal conditions).

VERIFYING THE PROBLEM
- With the engine cold, verify the radiator and expansion tank are properly filled, fill if necessary.

Thermostat Shut:

Thermostat Opens:

- Start the engine, warm up the cooling system and verify that the thermostat opens properly.

NOTE: Low coolant level or a stuck thermostat may prevent the electric cooling fan from operating properly.

- Continue to allow the engine to warm up, closely observing the cooling fan, engine temperature, and expansion tank. Check that the cooling fan energizes at the correct temperature.

CAUTION: Do not allow the engine to overheat. Turn off the engine before:
- Exceeding the normal operating temperature.
- Coolant expansion tank level exceeds the maximum.

QUICK CHECK OF COOLING FAN CIRCUIT
- Inspect:
- Cooling fan fuse.
- Cooling fan temperature switch and relay connections.
- Associated wiring.
- Verify the fan blades turn freely and smoothly.

CAUTION: When checking the fan blades for free travel and spin, always disconnect the negative battery terminal to prevent personal injury.