HVAC Noises and What They Tell You

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It can be disturbing and maybe even a little scary when you hear noises coming from your HVAC unit, and you’re not sure what they mean. The uncertainty is what really bothers you, because those noises might amount to nothing – or they might mean a total breakdown is imminent. The main thing to remember about such sounds is that they shouldn’t be ignored, because even if they don’t signify a major problem now, they could be caused by something which will develop into a major problem in the near future.

Unless you’re knowledgeable about heating and cooling systems, the safest thing to do is take note of the kinds of noises you hear, and pass that along to your expert neighborhood heating and cooling contractor. If you happen to live in the area around Phoenix, Scottsdale, Mesa, Tempe, Gilbert, or Chandler, that would be Bruce’s Air Conditioning and Heating.

Here’s what some of those noises mean, so you can discuss it with your HVAC specialists:

Clicking – it’s normal for the electrical components in an HVAC system to click during startup or shut down, but when it happens during operation, it could mean that you have a defective control or thermostat, because constant clicking is not normal.

Clanking – this is generally a sign of a loose part, or one that’s somehow out of balance. Sometimes it’s an indication that components within the sealed unit are failing, and sometimes it also means that the compressor has become loose. In still other cases, the blades of either the indoor blower or the outdoor fan may have gotten out of balance, and are striking other parts.

Banging – this is a pretty clear sign that some component or other is loose and is knocking against the frame or another part. Likely culprits are the crankshaft, the piston pin, or the connecting rod within the compressor of the air conditioning unit. It can also mean that your indoor blower is out of balance, or that your compressor is due for replacement.

Buzzing – there are a number of causes of buzzing from your outside unit, including debris, loose fan blades, failing condenser coil, clogged air filter, blower out of balance, refrigerant leaks, loose parts, or a loose outdoor fan motor.

Squealing – squeaks and squeals are generally transmitted by ductwork, but their actual sources are probably the outdoor fan motor or the indoor blower motor, both of which make loud squealing noises when they’re going bad. The blower wheel also makes a high-pitched squeaking noise when it begins to malfunction.

Humming – this is one of the less serious noises associated with your HVAC unit, but it can still mean that something is off internally. If ignored, it could lead to a more serious issue, so it should be checked out anyway.

Chattering – a chattering or rattling type of noise is usually a sign that your air-conditioning unit is beginning to go bad, and one or more parts are loosening. It can also sometimes mean that twigs, leaves and other debris have gotten inside your air-conditioning unit and clogged it.

Screaming – this is a fairly serious indication, and if you hear this, you should immediately shut the air conditioner off. The most likely cause of a screaming noise is a refrigerant leak, which in the early stages will affect performance, and in later stages can seriously damage the air conditioner.