Skip the auto shop - Our mechanics make house calls

Q: Heater fan or resistors bad

asked by on

The heater fan comes on and shuts back off

My car has 300 miles.
My car has a manual transmission.

Hi There, It sounds like you may have a faulty blower motor relay. The resistor controls the fan speeds and the relay controls the power to the motor itself. Occasionally, the blower motor itself will wear out or become faulty working intermittently as the brush contacts inside the motor wear out. The blower motor relay supplies power to this motor when you turn the switch to "on" that can sometimes fail. When this happens, you may notice that you will not feel anything blowing out of the vents at all. This may also cause the blower motor to work intermittently as you describe. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Heater fan or resistors bad

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car loses power, Check Engine Light is on, codes for EVAP system leak

If you have an air leak in the EVAP system then the MAP sensor will not be able to determine the air density, and the MAF sensor will not be able to determine the volume of air entering the engine...

Q: The vehicle sputters and hesitates after being started on humid days.

Hi there. Depending on where you live, the introduction of humidity in the air will also affect the air pressure around your vehicle. Higher altitude areas are impacted greater when barometric pressure changes. When air pressure is affected, engine vacuum...

Q: Vibration in car body when in Drive

The idle on your 2006 BMW 545i is automatically set by the computer, and if your idle is not within specifications, then you can have the throttle body and idle air valve cleaned. The motor and transmission mounts should be...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...