Air conditioner rattling may indicate one or more possible problems with the climate control system.

Car Air Conditioner Rattling and Troubleshooting

Hot cabin temperatures mean cranking up your car’s A/C, but what a disappointment it is when a rattling noise accompanies the air flow. On closer inspection of each vent, you might discover a foreign object such as paper or leaves caught between the slats. If there is no object present or the air conditioner rattling persists, then that noise may indicate one or more possible problems with the climate control system.

You can attribute climate control system rattling to one of several components. We’ll look at the most likely component first, then consider other parts that are potential noisemakers.

Inspect the Blower Motor

You’ll find your car’s blower motor located in one of two places. Usually, you’ll find it on the passenger side of the vehicle by opening the glove box and looking behind it. Otherwise, manufacturers may place the unit behind a plastic covering underneath the glove box. The other location is under the hood at the base of the firewall on the passenger side. There you’ll find a large cylinder, with a plate connecting the blower motor with the cylinder. If the blower motor rattles when the car idles, then replace it.

Find the Compressor Pulleyglove box

Bearings holding the compressor pulley in place may fail and make a racket. But the sound you’ll hear is typically a squealing, grinding or roaring noise, and that’s far different from rattling. If it is rattling you hear, then the pulley is not the issue.

Locate the Serpentine Belt

A car’s serpentine belt drives multiple components, including the engine, alternator, power steering pump, water pump and the air conditioner compressor. Typically, this is a screeching sound, although you may hear rattling, too. Examine the belt — if you find that the ribs facing the pulley are missing or some other pieces or the belt appear cracked, then replace it.

Inspect the Compressor Clutch

Another part that’s prone to wear is the compressor clutch. This particular clutch controls the compressor, which pressurizes and pumps refrigerant through the air conditioning system. A worn clutch tends to rattle. In this situation, you may need to replace both the clutch and the compressor to resolve the problem.

Consider Some Other Possibilities

If you have ruled out problems with the air conditioning system, there are other components under the hood that may rattle, too. For instance, before a water pump fails, it typically rattles, which may sound like marbles tossed about in a can when the car is idling. Also, a poorly aligned or slipping cam shaft belt may rattle.

Keep your car’s air conditioning system in top condition by routinely inspecting it per the owner’s manual guidelines. This includes replacing the cabin air filter as needed, cleaning the condenser and inspecting the cooling fan. An odd sound doesn’t necessarily accompany every problem, but you can avoid an issue and subsequent repairs with preventative maintenance.

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 and maintenance, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

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Matthew C. Keegan

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