Is Your HVAC Noisy?

Is Your HVAC Noisy? Look Out for These Warning Signs

Posted April 14, 2023

Creaking, screeching, grinding, clicking… is your HVAC noisy? Some of these sounds, while annoying, are harmless, while others need to be checked out by a professional right away. The key is knowing the difference between harmless and hazardous sounds. Here are the most common noises that come from your HVAC and whether you need to give your technician a call ASAP.

Clicking – Could Be a Sign of An Electrical Problem

It’s normal to hear a click or two when your heating and air system powers on to heat or cool your home. However, there may be an electrical issue with your system if you hear quickly repeating clicks coming from your outdoor unit.

The issue could be in your system’s relay switch, control board, capacitor or compressor. What you’re hearing is your system attempting to start, but not receiving enough electrical power to fully turn on – somewhat similar to when you try to start your vehicle with a dead battery.

NOISY HVAC ADVICE: Electrical issues, if ignored, can damage your heating and air conditioning system, be a fire hazard for your home, or pose a serious electrocution risk for you, your family and anyone else in your home or near your outdoor unit. If you notice constant clicking coming from your heating and air conditioning system, or it clicks repeatedly and won’t turn on, call a licensed heating and air conditioning company immediately.

Screeching or Squealing – Could Be Your Compressor

One of the most unpleasant sounds you may hear coming from your heating and air conditioning system is a screeching or squealing sound. Often, a squealing sound coming from your outdoor unit means that there’s a problem with your compressor or the bearings in the fan motor. The compressor applies pressure to the refrigerant in your system, and when you hear a squealing sound, it may mean that the compressor is not working properly.

NOISY HVAC ADVICE: If the screeching or squealing you hear is constant while your heating and air conditioning system is running, it could be bad bearings in your fan motor. Worn or bad bearings are one of the most common issues with heating and air conditioning equipment. If the bearing locks up, it could lead to overheating and further damage to your equipment. Scheduling an inspection is a good idea.

Grinding – Could Be Your Fan Motor

A grinding sound coming from your heat pump also indicates a potential issue with one of the fan motors or the compressor. You could have a bad bearing in the condenser or blower fans, a loose fan belt or a broken blade. You could also be hearing a worn out or bad valve in the compressor. Ultimately, if you hear a grinding noise, it means that one of your unit’s components is rubbing against another component in a way it’s not supposed to.

NOISY HVAC ADVICE: Parts grinding against other parts could quickly lead to a domino effect, damaging even more system components. If you hear a grinding noise coming from your heating and air conditioning system, call a heating and air conditioning contractor as soon as possible. This is another issue that can often be avoided by preventive maintenance.

Hissing – Could Be a Leak

A hissing sound coming from your outdoor unit could be a leak from your heating and air conditioning system’s compressor valve, a leaky refrigerant line or a leaky internal valve. These problems, if not fixed as soon as possible, could lead to worsening issues with your system. If you notice a constant hissing sound coming from your outdoor unit when it is running, contact a licensed heating and air contractor immediately.

NOISY HVAC ADVICE: Sometimes you also may hear short or periodical hissing coming from your unit. In most cases, this isn’t a problem. Your outdoor unit may hiss when pressure is released from the expansion valve. Your heating and air conditioning system’s expansion valve releases pressure that builds up from the refrigerant, which changes from liquid to vapor, and keeps your home cool.

Funny Noises and “Smoke” – Could be Defrost Mode

There are some cases where your outdoor unit might stop running, make funny noises, then emit what looks like smoke, but that’s likely just your system entering defrost mode. During the months your heater isn’t in use, dust can accumulate on the heating elements, and when you turn the heater on for the first time, the dust burns up and creates an unpleasant odor.

NOISY HVAC ADVICE: Don’t worry – the smell is perfectly normal and harmless. It will usually only last about 30 to 45 minutes, and likely won’t return until the same time next year.