How can you test a heater fan relay.

How do I tell if my heater relay has failed?

Signs that a Blower Motor Relay is Failing

1. Blower motor doesn't work. Blower motor not working is one of the first signs of a problem in the relay blower motor.
2. Blowing fuses. A blown circuit fuse in the AC blower motor relay circuit is one of the first signs of a failing or bad AC blower motor.
3. Melted relay.

Is there a fuse to power the heater blower as well? A relay, a fuse-like device that powers the blower motor, is used. Your heater and air conditioner may not be blowing air through the vents. This could indicate that your blower motor fuse is probably blowing. Although it is simple to replace your blower motor fuse, each vehicle may have a different location.

How can I tell if my blower motor resistor has gone bad?

A failed blower motor resistor can cause the heater fan to stop working at low speeds and only run at maximum speed (4 or 5). A failed blower motor resistor in some cars can cause the heater fan to stop functioning completely.

What can cause a fan relay's failure?

An engine or A/C condenser cooling fans that is not turning on can cause engine overheating and poor air conditioning performance. Many times, the problem is caused by a bad cooling fan relay. The cooling fan located in the engine compartment should be turned on to draw air through the radiator, A/C condenser and other components.