Troubleshooting
Loud Air Conditioner Outside
Quick answer
New noise = new problem. Banging is usually a loose part. Buzzing is electrical. Hissing is refrigerant. Grinding is the compressor — turn it off.
Common causes
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Banging
moderateLoose part inside the compressor or fan blade hitting something.
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Buzzing
moderateCapacitor or contactor failing. Electrical problem.
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Hissing
urgentRefrigerant leak. Stop running the unit; the compressor will burn up if it pumps without enough refrigerant.
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Squealing
moderateBad bearings in the fan motor. Will get worse fast.
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Grinding / metal-on-metal
urgentCompressor failing. Don't keep running it.
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Clicking
moderateNormal at startup/shutdown. Constant clicking = relay fault.
DIY first
- 1 Identify the noise type and when it happens (startup, mid-cycle, shutdown).
- 2 Look for visible debris on the fan blades.
Call us if:
- Hissing, grinding, or new metallic noises
- Noise getting louder over time
- AC also blowing warm air
Other symptoms in this category
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Mississauga, ON · Greater Toronto Area and up to 2 hours out — London, Kitchener, Barrie, Kingston, Niagara.