Car AC Squealing When Turned On?

Diagnosing car AC Squealing and Whining

Learn to Diagnose Squeals and Whining From Your Blower Motor

Do you have an annoying high-pitched squealing or whining noise while running the AC or heat in your car or truck, especially at low to medium speeds? Sometimes it’s because of debris in your blower motor, but other times it could be the blower motor or cage itself! In this post, we’ll discuss the difference between an old blower motor with a worn bearing and a brand new blower motor to see how an old one can make that awful noise.

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What Is a Blower Motor?

A car’s blower motor is an important part of its cooling and heating system. If it goes bad, you’ll have difficulty adjusting the temperature inside the cabin. This will not necessarily affect how the car operates. However, it will determine the level of comfort you and your passengers have especially when driving under extremely high or low temperatures. That annoying car AC squealing sound could be more serious than you may think.

If you notice any symptoms that show your car AC system is going bad, like whining and squealing sounds, it’s important to have it checked by a professional. There could be a problem with the blower motor. In some instances, it might fail completely and stop working. Here are some of the signs you can look out for before this happens. 

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

1. Unusual Noises

One of the more common symptoms of a bad blower motor is hearing unusual noises coming from the car’s HVAC system. This can be caused by foreign objects like sticks and leaves that get pulled into the engine compartment and find their way into the blower motor. 

If they get to the fan, they can damage the blades and snap them off easily. You’ll most likely hear slapping or popping noises coming from the vents. Another symptom would be hearing an ear screeching or squealing noise caused by wear and tear in the blower motor. 

The pitch changes as you adjust the speed of the motor. The bearings tend to age with time and start to produce sounds. You’ll need to have the blower motor replaced to fix the problem. 

2. Smoke or Smell

Sometimes, you may see smoke coming out or notice a burning smell when driving. This could be caused by a blower motor that’s burning. It’s advisable to stop the car immediately as this is often never a good sign. You should inspect your vehicle to confirm where the smoke is coming from. Once done, be sure to take it to a technician for a diagnosis and quick fix. 

3. Weak Airflow 

Blower motors tend to wear out over time. As such, it’s not uncommon for the airflow coming from the vents to weaken and diminish. This is often a sign that the motor is unable to push much of the air out of the HVAC system. You may start to notice less and less air coming out and even have a fan that doesn’t work at some speeds. 

This does not only cause poor airflow but also reduces the ability of the defroster to do its job. The defroster uses the blower motor fan to send air towards the windshield. Since several other parts could be causing the issue, it’s best to have your blower motor and HVAC system diagnosed by a technician to confirm that the problem is indeed with the blower motor. 

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

Checking for a bad blower motor

The very first step to diagnosing a bad blower motor in your car is to check the electrical system. Sometimes, failure can be caused by a bad fuse. Do a visual check to confirm that the fuse is not blown out. You can also swap it with a similar fuse that’s working well to confirm your suspicion. 

If the blower motor fuse is in good working condition, there could be a problem with the electrical wiring. Plugs could have gotten loose over time or they could have been accidentally knocked out. You may need a multimeter or probe to check the wiring once you confirm that everything is well put together. 

The next step would be to remove the motor and inspect it for any debris or junk. It could have stopped working physically due to foreign objects. Other than that, you may need to confirm that the motor spins freely without any noises or hiccups. If it does, this is a sign that you need a new blower motor. 

Replacing a bad blower motor is fairly easy. All you need to do is swap the old for the new. You can carry the old one as you head over to buy a replacement. This helps you to confirm that you’re getting the same part number for your car. 

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Car AC Squealing When Running - Diagnose Blower Noise - 1A Auto
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Car AC Squealing When Running - Diagnose Blower Noise - 1A Auto
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Do you have an annoying high-pitched squealing or whining noise while running the AC or heat in your car or truck, especially at low to medium speeds? Sometimes it's because of debris in your blower motor, but other times it could be the blower motor or cage itself!
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1A Auto
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