The cooling fan relay essentially
functions as the switch for the engine's cooling fans
, and is therefore an important electrical component of the vehicle's cooling system. … They will be able to look over your vehicle and replace your cooling fan relay if necessary.
How can you tell if a fan relay is bad?
- The engine runs hot or overheats. …
- The cooling fans don't work. …
- The cooling fans keep running. …
- Warning lights. …
- Poor air conditioning performance. …
- Swapping Relays. …
- Measuring the Relay Coil's Resistance. …
- Listening for Noises.
What is the purpose of a fan relay?
The function of the cooling fan relay is
to convert a low voltage signal from either the electronic control module (ECM) or a thermostatically controlled sensor
. The cooling fan relay takes the low voltage signal and internally switches the relay “on” to allow battery voltage to be supplied to the radiator cooling fan.
Where is the fan relay switch?
The fan relay is usually located
near the bottom of the engine compartment on a metal frame member
. The metal acts as a heat sink to keep the fan relay cool. So, unplug the connector at the relay and repeat the check for power. If you get power, you've got a bum relay.
Do cooling fan relays go bad?
If the cooling fan relay is going bad,
it can continue to run even when the ignition is off
, or when the engine is cold. On the opposite side, the fan may not operate at all which will cause the engine to overheat or the temperature gauge to rise.
Should radiator fan turn on when AC is on?
Both radiator fans should always run when the AC compressor is engaged. To check the temperature at which the fan comes on, turn the A/C off and keep the engine running until it reaches normal operating temperature. Most fans should come on when the coolant reaches
about 200 to 230 degrees
.
How do you test a fan relay switch?
- Look at the markings on top or side of the relay case and locate the two control circuit terminals, which connect to the relay's coil, and the two power circuit terminals, which let electrical current pass to the fan. …
- Connect the leads of an ohmmeter to the power terminals on the relay.
How do you check if a relay is working?
The only tool required to check a relay is
a multimeter
. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located).
How much does a fan relay cost?
To get your cooling fan relay replaced, you will pay, on average,
$80-$160
, depending on the type of car you have and the mechanic's fees. The labor should cost around $70, while parts should run you $10-$50.
What sensor controls the radiator fan?
On most modern cars, the cooling fan is controlled by
the Engine Control Unit (ECU)
which gets a signal from the coolant temperature sensor.
Why does my radiator fan not turn on?
If the fan doesn't come on,
you need to look for a blown fuse or breaker
. In older cars, you might have a fusible link – this is wire within an insulated block of rubber. Try to grab the end and stretch it. If the wire stretches, the wire link could be broken and you'll need to replace it.
What tells the cooling fan to come on?
The engine temperature should trigger the fan to turn on
. It will also turn the fan off once the engine has cooled to under 200 degrees. You may have heard of a part called the radiator fan switch or temperature fan switch. This is linked to a thermostat and works much like your home's HVAC system.
How do I know if my radiator fan fuse is bad?
- Engine Overheating. When the radiator fan isn't functioning properly, it is not able to adequately cool down the car's engine. …
- Air Conditioner Function Diminished. …
- Loud Noise Coming From Radiator Fan.
What causes a fan to stop working?
Poor ventilation can cause dust and heat to get trapped inside the case of the motor
. This can cause your fan to stop functioning—especially if your fan has an overheating feature that causes it to automatically shut off if it gets too hot.
