3 Explanations For Your Car's Noisy AC System

Your car's air conditioning system has one job: keep you cool on the hottest summer days. Of course, you always want your air conditioner to be as reliable and unobtrusive as possible. A system that makes a loud racket as you drive along can be annoying, and these sounds often indicate an underlying issue that may eventually affect its ability to cool your cabin.

As with other automotive noises, you should treat sounds from your air conditioning system as an early warning sign and cause for concern. While the sound of whooshing air (especially at higher fan speeds) may be normal, these other three noises are worth further investigation.

1. Roaring or Humming

A loud roaring or humming noise is a warning sign of a failing bearing in your air conditioning blower motor. Most cars use variable-speed blowers that you can adjust with a dial on the dash or that adjust automatically based on commands from the car's climate control system. Like many fans, the bearing is a common failure point.

As the bearing wears out, it often produces a noticeable roaring or humming sound, especially at higher fan speeds. You can rule out other issues by switching off the AC and turning the fan on high. If you can still hear the noise with the air conditioner turned off, the blower is likely to blame. Issues with your blower will eventually stop your AC from working, so you shouldn't wait long to address this problem.

2. Banging or Knocking

Loud banging or knocking from your car's air conditioning system can often indicate a worst-case scenario. If you can hear this sound from under your car's hood whenever the AC turns on, you're probably hearing the compressor. The compressor is the most expensive and crucial part of your air conditioning system and it will not function at all if the compressor fails.

Banging can occur due to liquid refrigerant entering the compressor, which can cause severe damage. This condition (known as slugging) usually occurs due to problems elsewhere in the system, but it can quickly cause internal damage to the compressor. Treat this noise as a flashing red warning sign and avoid using your car's AC until an experienced shop can investigate.

3. Clicking or Tapping

Clicking and tapping sounds are relatively common with AC systems and are often not a severe problem. If you can hear a constant tapping while your AC runs, the source may be debris or contaminants trapped in the ductwork. Sometimes, the problem may be with a leaf or other object stuck on the fresh air vents outside your car or even something trapped against your cabin AC filter.

Start by checking these easy-to-access locations and removing anything you find. Replacing your cabin filter can also help, especially if you haven't changed it recently. If these simple steps don't resolve the problem, you will likely need an experienced shop to look for loose components that may be vibrating or moving while your AC system runs.

For more information on auto AC repair, contact a professional near you.