Dan Ferrell writes on auto maintenance and repair on his own account. It has certifications in automation and control technology.
Cooling fan problems can be difficult to diagnose, depending on your vehicle model and the type of failure. Still, you can avoid much of the confusion by using a troubleshooting plan.
If the electric radiator fan won’t turn on after the engine reaches operating temperature, the key here is operating temperature (more on that later), you can bet there is something wrong with the fan assembly, the circuit or one of its components. .
This guide walks you through some of the more common electric cooling fan problems to help you troubleshoot and identify the problem when the fan refuses to run or runs intermittently.
On older vehicle models, the fan circuit is simple and you may have no trouble locating operating components or the fault itself.
Modern vehicles use the electronic control module (car ECM-computer), the powertrain control module (PCM), or a dedicated fan control module (or both) to control the operation of the radiator fan, and sometimes it can be a bit more difficult to troubleshoot.
Therefore, with newer vehicle models, it is a good idea to have the vehicle repair manual handy for your particular make and model, especially with fairly recent models. The manual explains how the cooling system works, how your cooling fan works, and the sensors or switches your car’s computer reads to operate the cooling fan. Also, the manual can help you locate sensors, relays, switches, and trace circuit wires as needed. Haynes makes good aftermarket manuals.
If your engine is overheating and you suspect cooling fan problems, this guide gives you important troubleshooting tips and steps to diagnose the most common cooling fan faults you are likely to find in your car.
If your cooling fan runs continuously, check the fan relay or the cooling fan temperature switch, or the engine coolant temperature (ECT) sensor.
However, before taking the steps to troubleshoot your vehicle’s fan, a brief description of how the fan works is included.
In this article:
Cooling fan operation
Cooling fan troubleshooting
- Has your cooling fan really failed?
- How to test the cooling fan motor
- Checking cables, connectors, and related components
- Cooling fan temperature switch test
- Testing a cooling fan relay
How the cooling fan works
If your vehicle’s cooling system uses an electric cooling fan, it most likely has a transverse (side) mounted motor. However, some longitudinally (front-to-rear) mounted motors also use the electric fan, but generally have a motor-driven cooling fan.
The electric cooling fan uses a direct current (DC) electric motor with a thermal switch, module, or computer control to turn it on or off, depending on the coolant temperature or AC operating conditions.
In older fan circuits, the thermostatic switch connects to battery power on one side and the fan motor on the other. However, on most of the ’90s and newer models, control was passed to the car’s computer or a dedicated module. For example, when the coolant temperature changes, the thermal switch reports this change to the computer through a voltage signal, which the computer or module uses to activate the cooling fan through a fan relay.
An electric cooling fan not only helps save energy by operating only when the system needs to remove excess heat from the motor, …