What is the Thermo Coolant Fan Switch all about?

The cooling fan on your car only runs when the engine temperature is hot due to a thermo cooling fan switch. It is mounted on the engine and detects the temperature of the engine as a simple electrical two-wire switch. When the temperature reaches the set value for the switch, it completes a circuit inside that initiates the cooling fan operation. When the temperature drops below a set threshold, the cooling fan turns off. If the thermo cooling fan switch is faulty, the cooling fan may run all the time even if the engine is off, or the cooling fan may not turn on at all when the engine temperature is too high.

Keep in mind:

• Your engine’s thermostat is vital for preventing overheating.
• The cooling fan can continue to run even when the engine is shut off.

How it's done:

• The coolant is allowed to cool and then drained
• The defective thermo coolant fan switch electrical connector is detached from the switch and the switch removed.
• The new thermo coolant fan switch is installed and the electrical connector is connected
• The coolant is filled and coolant system is bled of air
• The engine is ran and cleared of codes and road tested for proper cooling fan operation

Our recommendation:

The cooling fan switch will likely last the life of your vehicle, though it can fail unexpectedly as electrical components are prone to do. If that happens or if you suspect the thermo cooling fan switch is faulty, have one of our expert mechanics diagnose it.

What common symptoms indicate you may need to replace the Thermo Coolant Fan Switch?

• Check Engine light is on
• Cooling fan isn’t turning on
• Engine temperature is above normal or the engine hot warning is on

How important is this service?

Because catastrophic engine failure can occur from overheating, it is important to replace the thermo cooling fan switch as soon as it has been diagnosed as faulty.