Signs of a Failing Radiator Fan

All vehicles use a radiator fan to help remove heat from the coolant that circulates through the engine. The fan also cools your air conditioning refrigerant, and is sometimes called a “condenser fan” or “cooling system fan.”

There are two basic types of radiator fans: mechanical and electric.

Mechanical: These are usually found in older, rear-wheel drive vehicles, as well as some modern trucks. Most mechanical fans have a built-in clutch that allows the fan to idle when the engine is cold and rotate when it’s hot. Mechanical fans typically mount to the water pump pulley at the front of the engine.

Electric: These are used in most modern vehicles and are driven by an electric motor. The engine’s computer decides when to turn on the fan.

When you drive, air is forced through the grille, through the condenser and through the radiator. The air removes heat from the coolant and the A/C system. But when the vehicle is idling or moving slowly, too little air enters to keep things cool. That’s where the radiator fan comes in.

The fan moves air through the radiator and condenser to keep removing heat from both units. On some modern vehicles, the fan may come on at higher speeds as well to supplement the airflow.

Some cars have two electric cooling fans.

Signs of a failing radiator fan

A faulty radiator fan can cause many problems. These are some of the most common:

• Engine overheating: A bad radiator fan can cause the engine to overheat, especially at low speeds. If your car starts overheating, pull off the road as quickly as you safely can and turn off the engine. An overheated engine can quickly get ruined and lead to expensive repair bills.
• A/C blows warm air: The condenser, with help from the radiator fan, is responsible for eliminating heat from the A/C system. If the fan fails, the condenser can’t do its job and the A/C system will blow warm air.
• Warning lights are on: A faulty radiator fan can trigger warning lights such as the engine temperature and check engine lights. In some cases, the A/C system may also display some type of warning, such as a flashing A/C button.

» MORE: Get an estimate for your radiator fan replacement

How to fix the problem

A failed radiator fan should be replaced immediately. Allowing an engine to overheat even once can cause extensive damage. Have your vehicle diagnosed by a professional immediately if you suspect fan issues.

Typically, it’s possible to replace just the motor on an electric fan, instead of the complete assembly. A mechanical fan clutch can usually be serviced separately, as well. Drivers without much repair experience should leave these tasks to a professional repair shop.