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10 Loud Noises My Air Conditioner Is Making

Air Conditioner Making Loud Noises

An air conditioner is a complex appliance, with lots of moving parts that tend to make noise, especially when you own an older model.

But even if you’re used to a certain amount of noise from your central air conditioner system, pay attention to sudden, unusual LOUD sounds. And check this list to find which noises spell trouble for your A/C.


Whether you hear loud buzzing noises indoors or outside, beware! It’s not an angry swarm of hornets nesting in your A/C unit, but rather the warning signal of electrical problems like:

  • Loose wires
  • Motor going bad
  • Capacitor damage
  • Compressor malfunction
  • Or if you see sparks, electrical arcing


Some air conditioning systems naturally make a squealing noise when first starting up. Unfortunately, you just have to live with that.

However, if this type of sound is new, listen carefully to what it’s trying to tell you. Squealing could indicate either a blower wheel malfunction or a dying indoor blower or outdoor fan motor. A/C repair or even replacement could be necessary.


There are two distinct types of clicking noises a central air conditioning system might make. Fortunately, the difference is obvious.

With the first, you can switch your unit on, although the clicks get faster and closer together as it powers up. The most common cause? A foreign object in the outdoor unit, which you can easily remove.

If you have the second, the machine will make noise yet not actually start operating. Here you’re probably facing an electrical problem — likely the capacitor, compressor, or broken thermostat.


Usually a humming noise points to a minor issue. (Whew!) You should still get it seen to, however, before a small problem (like loose wiring or refrigerant piping) turns into a big headache. And there’s an off-chance the hum is caused by a faulty motor.


Check the outdoor unit; a rattling noise may be the result of debris (like leaves or twigs) that’s fallen into the vents. If so, simply clear it out … and prune back the shrubbery around the unit.

Otherwise, the rattling could be caused by loose fasteners. Once again, this is not a major problem.

Worst case scenario: The compressor motor is about to fail.


When your A/C hisses at you, don’t take it personally. Ageing HVAC ductwork may be the culprit. If it’s apparent that the hissing noise stems from the air conditioner itself, a refrigerant leak may be to blame.


You’ll hear banging if the outdoor air conditioning unit’s fan is in trouble. Possibly, something’s getting in the way of its blades (a minor issue). On the other hand, the fan may have worked its way loose from its mounting.


Liquid is the culprit when your air conditioner begins bubbling. Could be the condensate drain line is just making itself heard, which is nothing to worry about. If there’s a refrigerant leak, though, the unit needs professional air conditioner repair.


Take screeching very seriously. A squeal as of metal on metal from your outside unit tells you that the fan motor or the compressor has given out. You need replacement parts pronto.

Indoors, that screech signifies your blower fan motor should get new bearings or a new belt.


This is also bad news. High-pitched whistling could mean a refrigerant leak, which is bad for your A/C and worse for your indoor air quality … and your health. Equally nasty, whistling sometimes indicates dangerously high internal pressure in your air compressor.

Find Air Conditioning Solutions With Ottawa Home Services

If your A/C is acting up, contact Ottawa Home Services at 613-604-4777. We’re here to offer you options that work, whether you want air conditioning repair, A/C rental program, or a brand new Mitsubishi system.


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