Skip the auto shop - Our mechanics make house calls

Q: hvac blower not working and 30A fuse blown

asked by on

blower not working in car, checked and 30A hvac blower fuse was blown replaced and blew again

My car has 100200 miles.
My car has an automatic transmission.

That 30A fuse powers what is historically known as a blower motor resistor. In the case of your car it is a small computer called the blower motor control processor. It is simply a blower fan speed control. I would remove it and see if it looks melted or appears to have been really hot. I would expect you to find something like this, as this is a very common failure on all vehicles.

It is mounted on the passenger side above their feet, near the blower motor. It has five wires coming out of it. If once you have located this and removed it you don’t see anything physically wrong with it, I would unplug the connector to it and plug in another fuse. If the fuse doesn’t blow, you can be assured the wire coming from the fuse box is good. If the fuse blows with the blower resistor disconnected, then you have a wire shorted to ground somewhere from the fuse box to the resistor. Now you will need to locate it. I recommend running a new wire altogether if this is the case. Finding a shorted wire in the harness that runs through your dash will take many hours.

If the fuse doesn’t blow, the likely culprit is the blower motor controller. If there isn’t a sign of melting or being hot, I would power the blower motor with a jumper wire to see what it does. Ideally, you need an inductive amp clamp to monitor how much current the blower motor is pulling. If it exceeds 30 amps for a sustained period of time, I would replace it. Keep in mind, when an electric motor first starts working, the current will spike. Most likely above 30 amps. This is normal. What you want to monitor is the sustained current when the motor is operating. Most electrical systems such as this should run a current %50 to %70 of the maximum. Which in this case is 30 amps.

If there is a problem with the motor, you will likely have other indicators like, the motor won’t run, or it will get really hot to the touch. If you have determined there is a problem with the blower motor, I would advise you to replace the blower motor controller as well. They don’t take kindly to higher than designed electrical currents and it is likely damaged. Lastly, if the blower motor controller has been hot or melted, test the blower motor to make sure it isn’t pulling excessive current.

If you feel like you need some assistance with this, feel free to contact a certified mechanic who can diagnose your electrical issue with your blower motor resistor. Once that is done, they can assist you with replace your blower motor resistor as necessary and ensure that it’s properly functioning.

Good luck.

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!

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: power steering

You want to make sure the system is fully bled and there is no trapped air. Also check drive belt tension to be sure the pump is getting sufficient power. If pump output pressure is within spec (it would have...

Q: My steering wheel in my 2004 chevy cavalier is tight and stiff

Make sure that your tires are not under inflated in the front. If there is adequate power steering fluid and the belt driving the pump pulley is properly tensioned, the output pressure of the pump should be measured. If the...

Q: Noise when turning the steering wheel.

Hello. Noises when you turn the wheel can be caused by many things. A few common causes are worn steering or suspension components, or as you stated a problem with the power steering pump or system. The steering and suspension...

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...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...