Car squeals when AC is on

2000 MAZDA PROTEGE

140,000 MILES • 0.6L • 4 CYL • 2WD • AUTOMATIC

RACHRACH

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I have a 2000 Mazda Protege with these problems:

I consistently hear an insanely loud and high-pitched squeal in the following situations:
-when I first turn on the air conditioner
-when I accelerate after first turning the AC on

I sometimes hear the same noise when:
-I turn on the air (without AC)
-I start my car on a fairly cold morning
-I defrost the windows

I've brought the car to my mechanic for this issue several times over the past few years. I had the belts changed one of those times. The squealing stopped for a few days but then came back as irritating as ever. I brought it back a few months ago and he said the sound "is normal"...which is bull.

I'm looking into getting a new mechanic, I just haven't had the time to get it checked again in recent months.

I've been told the following by friends/family/previous searches: loose belt, wrong sized belt, something wrong with the AC unit.

I mostly am wondering 1) what the problem is and 2) if I can fix it myself.

Thank you!

Sep 11, 2015 at 11:44 AM

CARADIODOC

CERTIFIED EXPERT
34,306 POSTS

Based on the information you've provided, the high-pitched squealing noise you're experiencing in various situations, especially when you turn on the air conditioner, could be due to a few possible causes. Here are some potential explanations:

Belt Tension: One possibility is that the serpentine belt or one of the accessory belts in your vehicle's engine is not properly tensioned. If the belt is loose or worn, it can slip when you engage the air conditioner or other accessories, causing the squealing noise. You mentioned that you had the belts changed before, but it's possible that the tension was not adjusted correctly. It would be worth checking the belt tension or having it checked by a mechanic.

Belt Condition: Even if the belt tension is correct, the belt itself may be worn, glazed, or damaged, leading to the squealing noise. Over time, belts can develop cracks or lose their grip, causing them to slip and produce the sound you're hearing. If the belt is in poor condition, it may need to be replaced.

AC Compressor Issues: The squealing noise could also be related to a problem with the air conditioning compressor itself. If the compressor is failing or not functioning properly, it can put extra strain on the belt and cause it to slip. In this case, repairing or replacing the AC compressor would be necessary.

As for whether you can fix it yourself, it depends on your mechanical experience and comfort level. Checking the belt tension and condition is something you can do yourself with the right tools and guidance from a repair manual specific to your Mazda Protege model. However, diagnosing and repairing AC compressor issues might require specialized equipment and expertise, so it's generally recommended to have a qualified mechanic inspect and address that aspect of the problem.

Since you're considering finding a new mechanic, it's a good idea to seek recommendations from friends or family, read reviews, and choose a reputable professional who has experience with Mazda vehicles. They can properly diagnose the issue and provide an accurate solution.

Remember that diagnosing automotive issues can sometimes be challenging, and it's essential to address them properly to ensure the safety and reliability of your vehicle.

Sep 13, 2015 at 8:24 PM