However, in most '90s and newer models, the control was passed to the car computer or a dedicated module.

On older fan circuits, the thermostatic switch connects to battery power on one side, and to the fan motor on the other. The electric cooling fan uses a direct current (DC) electric motor with a thermo switch, module or computer control to turn it on or off, depending on coolant temperature or AC operating condition. However, some longitudinal (front to rear) mounted engines use the electric fan as well, but they usually have an engine-powered cooling fan.

If the cooling system in your vehicle uses an electric cooling fan, most likely you have a transversal (sideways) mounted engine. Besides, the manual can help you locate sensors, relays, switches, and trace circuit wires as necessary. The manual explains the operation of the cooling system, how your cooling fan operates, and the sensors or switches your car computer reads from to operate the cooling fan. So, with newer vehicle models, it's a good idea to have the vehicle repair manual for your particular make and model on hand, especially with fairly recent models. Modern vehicles use the electronic control module (ECM-car computer), powertrain control module (PCM), or a dedicated fan control module (or both) to control the operation of the radiator fan, and can be a little more complicated to troubleshoot sometimes. On older vehicle models, the fan circuit is simple, and you may not have trouble locating operating components or the fault itself. This guide walks you through some of the most common electric cooling fan problems to help you troubleshoot and identify the problem when the fan refuses to work or works intermittently. If your electric radiator fan isn't coming on after the engine reaches operating temperature-the key here is operating temperature (more on this later)-you can bet there's something wrong with the fan assembly itself, the circuit, or one of its components.

Change coolant temperature sensor