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5 Air Conditioning Noises and Their Causes

Summertime—it’s sunshine, warm breezes, barbecues and the gentle hum of air conditioners keeping houses cool throughout the neighborhood. In a split second, that gentle hum can turn into an unnerving hissing, banging or screeching. While all air conditioners make noise, it’s important to be able to recognize which noises are normal, and which noises require a professional inspection.

1. Hissing

Uh oh! More than likely, you’ve sprung a leak. Usually, a hissing sound indicates that your air conditioner is leaking refrigerant. In some cases, there’s a small opening in one of the refrigerant lines. In others, there may be an internal valve leak.

If the hissing is really loud and accompanied by squealing or screeching from the compressor, you need to turn off your air conditioner immediately. This indicates that there is too much pressure in the compressor, which could lead to a costly repair bill if you don’t act soon.

2. Screeching

One of the most startling noises is generally one of the easiest to diagnose. In newer direct-drive A/C units, you can trace a screeching noise to a shot bearing in the fan motor. Usually, you’ll have to replace the fan motor to get the noise to stop. In older A/C units, the screech could be coming from the belt that connects the motor to the blower. Belts gradually wear down, and you need to replace them from time to time.

3. Banging

A loud banging or rattling can mean that there’s a loose part somewhere in your A/C unit. Before more damage occurs, you’ll want to shut of the air conditioner as soon as you hear the noise. Is the noise louder outside of your house or inside of it? If it’s outside, one of the fan blades could have come loose in the compressor. If the noise is louder inside, your blower fan might be causing the racket.

4. Clicking

Hearing a clicking sound when the air conditioner kicks on is common and completely normal. That click is how your thermostat communicates with the unit. However, when it’s on, your A/C shouldn’t be ticking like a clock.

Like banging noises, clicking often comes from a loose or damaged part that’s hitting against something that it normally wouldn’t. An occasional clicking noise could indicate that there’s something stuck in one of the airways. On the other hand, if the clicking is constantly coming from your thermostat, there could be an issue with the circuit board.

5. Buzzing

A couple of issues could make your air conditioning unit buzz, like a swarm of hornets building a nest in your outside unit. If you can rule out pests, the buzzing could be coming from loose parts rubbing together, or your air conditioner might have frozen up. If you see a buildup of frost and ice on the unit, a professional can help you determine the cause. Finally, listen to hear if the buzzing sound is coming from the unit’s power source. The A/C could be overloading your circuit panel, which will require a professional evaluation.

If your air conditioner is making a noise that it shouldn’t, call Althoff.

Ignoring the problem could cause damage to your unit that then requires more extensive repairs. Have one of our licensed Chicago HVAC technicians check out the sound now and get peace of mind. Contact us at 800-225-2443 to schedule.

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