Skip the auto shop - Our mechanics make house calls

Q: AC/heater not blowing on high.

asked by on

The AC/heater is making a humming sound and not blowing when on high. It works fine on lower settings. I changed the blower resistor, but it is still doing this.

A: Having your AC and Heater make a humming no...

Having your AC and Heater make a humming noise while running on high can be an annoying occurrence while you are trying to enjoy driving your truck. Since the problem is persisting after replacing the blower motor resistor, there are two possible problems. You may have a faulty new part or the problem lies not in the resistor but in the blower motor itself.

If you were able to replace the resistor yourself, then you may feel comfortable inspecting the blower motor as well. Without the proper tools and experience it will be difficult to diagnose the problem if it is electrical, but with dropping down the blower motor it may reveal a problem you can see visually. The blower motor is exposed to the outside air and, despite having a filter that strains out pollen and debris, it is still possible that something may be obstructing it from blowing air on the highest setting. Rather than take a guess and possibly waste money however, I highly recommend enlisting the help of a certified mechanic. With their aid you can get the proper diagnosis and get your blower motor operating normal again.

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: My truck tries to start with the key in the off position. Changed out the starter but is still doing it.

There may be a short in the starter / ignition system. If the starter solenoid was not replaced, that can be a culprit. It may or may not be the cause. I had one of my own vehicles engage the...

Q: No heat-

If the heater hoses both are hot shows good flow through the heater core. The temperature control actuator is behind the glove box. You should operate the temperature control and see if the actuator is moving the blend door? If...

Q: Air conditioner condensation does not drain

Hello. We will be happy to assist. Most likely you have an AC drain port that is clogged. It's best to blow out the drain port with compressed air to ensure there is a clear drain passage. If there is...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.