Climate controls

Air Conditioner Rattling: 4 Common Causes

Is your air conditioner rattling and starting to make you worry about a potentially extensive repair in the near future? You’re right to be concerned, because a rattle is often a sign that there’s something amiss in your climate control system.

Not all rattles have the same source, and not every AC repair is a complex one. Check out these four common causes of air conditioning rattles to begin diagnosing yours.

1. Belt Tensioner

A belt tensioner is the most common cause of air conditioner rattling. Fortunately, it’s fairly easy to replace. The tensioner is a part at the front of your engine that ensures the serpentine belt that drives the air conditioner pulley stays as tight as possible at all times. Eventually, the spring in the tensioner can start to fail, which leads to a rattling sound.

Climate controls

2. Belt Noise

If your car’s drive, or serpentine, belt is itself starting to wear out, it can also cause a rattling sound when you use your air conditioner. This is because kicking on the AC puts more of a load on the belt, which can expose any weaknesses that could be causing it to move unevenly through the pulleys.

3. Compressor

Air conditioner rattle that’s caused by the compressor requires the most complex repair, because the compressor is the most vital component to the operation of your AC. The compressor contains many moving parts and it can wear out internally over time, causing a rattle that will manifest every time it clicks on. On occasion, the compressor clutch might be the culprit instead of the compressor itself. On some vehicles, it’s possible to replace just the clutch rather than the entire unit. It’s worth asking your mechanic if they can be serviced separately should you suspect that this is the problem.

4. Pulleys

Why not a specific pulley? Well, when you engage the AC in your car or truck, it adds extra strain to your motor, which can cause any unrelated pulleys that might be wearing out to show their true colors. Often, an idler pulley or power-steering pump pulley is the source of unusual sounds associated with your air conditioning. It’s worth checking your vehicle beyond the usual AC suspects if you can’t easily locate the source of the noise.

Air conditioner rattling can be a nuisance and even a sign of serious damage. Many sources of rattling are easy to handle at home, but make sure to consult a mechanic if the damage is extensive or involves the compressor.

For more information on dealing with air conditioner rattling, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Check out all the air conditioning parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on air conditioner rattling, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Wikimedia Commons.

about author

Benjamin Hunting

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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