Car AC Squealing When Turned On?

Car AC Squealing When Turned On?
Posted in: How To and Tips

Learn to Diagnose Squeals and Whining From Your Blower Motor

Let’s say you’re driving along, then you suddenly hear a strange squeaking noise from your AC. You’ve never heard your car make a sound like that. Where could this annoying, high pitched noise be coming from? It might be an old blower motor. And the noise it makes isn’t just an annoyance; if ignored, it can cause much larger issues for your car. Why is it making this noise? How can I fix it? In this blog, we’ll talk all about these problems, and then how to fix them.

What Is a Blower Motor?

The blower motor plays a huge role in the vehicle cooling and heating system. The blower motor’s function is to push cold or hot air through your vehicle. When it fails, your car cannot maintain a comfortable temperature year-round. It might sound like a minor annoyance, but driving under extreme temperatures, high or low, is more dangerous for drivers than you might think!

If your AC shows any of the signs it’s going bad, like a dreaded squealing noise, you should have it taken to the shop right away. If you continue to ignore the problem, it can eventually lead to the complete failure of your AC system. If you’re not sure whether your blower motor is broken, here are some signs for you to watch out for.

Car AC Squealing and Other Signs Your Vehicle’s Blower Motor is Going Bad

  1. Unusual Noises - The most common symptom of a bad blower motor are strange noises coming from your AC. The strange sounds you’re hearing might be stuck debris. Objects like sticks and leaves can get sucked in through your engine compartment and get stuck in your HVAC system.

    If the debris gets to your fan it can cause damage to your AC blades, and the broken blades can snap and fall off. This gradual damage to your blower motor can also cause screeching or squealing sounds from your HVAC.

    What’s another noise to watch out for? You might experience strange pitch changes when you adjust your motor speed. These pitch changes are caused by the natural degradation of your vehicle’s motor bearings. The noises won’t stop until your car’s blower motor is replaced.

  2. Smoke or Smell - AC malfunction doesn’t always cause noises; sometimes you can see or smell the symptoms. One of the more urgent signs of AC malfunction is a burning smell. You might even see smoke coming out of your AC while you’re driving. If you ever experience any of these symptoms while driving, you should stop the car immediately. Then take your car to a technician as soon as possible. They’ll be able to tell where the smoke is coming from and get it fixed.
  3. Weak Airflow - Blower motors do not always have obvious causes for their damage, they gradually weaken over their lifetime. When blower motors get worn, the airflow from your vents drops and you’ll notice less and less air coming out of your HVAC system. The fan might no longer work at some speeds.

    An old blower motor doesn’t just give you bad airflow, it’ll also make your defroster much less effective. Then you won’t be able to see while driving in bad weather. Don’t wait until you find yourself in a dangerous situation, and make sure to have your HVAC checked by a technician

How to Check a Bad Blower Motor That’s Making Squealing Sounds

There are lots of possible symptoms of a blower motor problem, but how do you know for sure? If you want to diagnose a bad blower motor, the first thing you should do is check your car’s electrical systems. A failing blower motor could be caused by a blown fuse. If you can’t tell if the fuse is blown or not, you can also swap it out with a healthy fuse and see if that fixes the problem.

If your blower motor fuse is fine, but you’re still experiencing symptoms, it might be a problem with your car’s electrical wiring. Maybe one of your electrical plugs got loose. In order to diagnose wiring problems, you’ll need to use a multimeter or a probe.

If your fuse is fine, and your wiring is well put together, you can also remove your motor and inspect it for any debris that may have gotten caught. You can also check how well your motor spins. If you notice any noises while it’s spinning, or it doesn’t spin smoothly, you know you’ll need to get your blower motor replaced.


If you’ve never had to replace a blower motor, it’s a surprisingly simple task. Just remove the old blower motor and swap it out with a new blower motor. To make sure you are getting the right parts visit PartsHawk.com and use our detailed year, make, and model search to find the best matching parts available. If you are still unsure, remove the old blower motor first and then compare the numbers and manufacturer. You can also contact us at (650) 560-HAWK with any questions.

2 months ago
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