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Why Your Air Conditioner Sounds Like That

Why Your Air Conditioner Sounds Like That

Noisy operation isn’t part of normal air conditioner aging, especially with today’s quiet units. If your air conditioner recently started making a strange noise, have it inspected right away - the longer you put it off, the more damage you could be doing to the unit, which will ultimately shorten its life and cost you more money for an early replacement. Listen for these common sounds to determine where the problem might be.

1) Clanging, Banging or Knocking

If you have an outdoor unit, it may make banging or knocking noises if the fan is hitting debris or if the fan is coming loose from its mount. Banging could also mean a broken or loose part inside the compressor or an unbalanced indoor blower. In all of these cases, you need to turn the AC off until the problem is fixed.

2) Buzzing or Humming

A buzzing sound from an outside unit could mean any number of things, from loose parts that are vibrating against other parts to debris, unbalanced fan blades or a condenser coil that’s in need of a cleaning. If the buzzing is accompanied by no cooling, it could mean a refrigerant leak that’s causing your air conditioning unit to freeze up.

3) Screeching or Shrieking

A metal-on-metal noise that doesn’t stop until the unit shuts off can indicate that the fan motor bearings have failed. If that’s the case, you need a new fan motor.

4) Squealing

A squealing noise coming from an inside unit that doesn’t normally make that noise is likely a blower wheel and housing, motor, or misaligned or failing fan belt. This belt, which connects the fan and motor in some units, can fall out of alignment or wear out over time. You might notice that the sound comes and goes; this is from the belt expanding and contracting in response to different temperatures and levels of humidity. You can still run the unit while you’re waiting for service, but if you wait too long, the belt could break and leave you without cooling. Some units squeal when they start up even when they’re in great shape, though, so the key with squealing noises is to be aware of whether the unit always makes that sound or if the noise is new.

5) Clicking

The cause of a clicking noise can come from two sources depending on the behavior of the rest of the unit. If you hear clicking but can’t get the outside AC to turn on, you probably have an electrical problem in the thermostat, compressor or capacitor. If the unit does run, but the clicking continues, you might have a failing thermostat or controls on your hands that you need to have replaced before they fail completely. Clicks that become faster and closer together as the unit ramps up are probably just a small obstruction in the fan that you need to remove.

6) Bubbling or Gurgling

If you hear a liquid gurgling noise that you can’t quite pin down the location of, you could have an issue with the condensate drain line or a refrigerant leak. Check to see if the drain line has a proper trap. If it seems more like a refrigerant leak, have a professional examine it.

7) Screaming or High-Pitched Hissing

If you hear a screaming or hissing sound from your air conditioning unit, stop what you’re doing and turn the AC off. This sound, which you’ll notice for about 10-15 seconds when the outside AC first turns on, is usually either a refrigerant leak or high pressure building up in your compressor, both of which can be extremely dangerous. Don’t turn the air conditioning back on until a professional can come out and fix it. The unit should have a safety switch that shuts the AC down when it detects high pressure, but be proactive instead of relying on the switch, which could malfunction just like any other part.