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Serving The Northland

Serving the Northland


Mesaba Heating & Air Conditioning Blog

What Noises CAN Your AC Make?


We all know that a funny noise can indicate a problem with a complex system, whether that’s a car, dishwasher, furnace, or your air conditioner. But sometimes it can be hard to tell whether a sound might mean something is wrong or if it is a perfectly normal noise that you shouldn’t worry about. While it’s good to know what AC noises mean it’s time to call for repairs, it’s also good to know what noises are just the sound of normal operation. Here’s a rundown of the sounds that a perfectly-happy air conditioner might make while it’s running smoothly.


The fan of your air conditioner makes a whirring sound. Depending on the model of air conditioner you have, it may run all the time, or only during cooling cycles, or it may have different settings you can choose. This fan is not just pushing cool air out of your vents. It’s also pushing the air across the evaporator coils, which allows the refrigerant within them to absorb the heat from that air. This whir is a necessary sound, and the only thing that should concern you about it is if you don’t hear it at all.


The compressor makes a low hum during cooling cycles. It is located in the outdoor unit of your air conditioner, and it pressurizes the refrigerant, forcing it to flow through the coils. When your thermostat gives the signal that your home is getting too warm, the compressor kicks on, and when it reaches a cool enough temperature, it will shut off again. The only reason to be concerned about this noise is if it is starting and stopping every couple of minutes, which is a problem called short cycling. 


Since your air is being cooled by blowing across super-cold evaporator coils, some moisture will be pulled out of that air, just like the condensation that develops on the outside of a glass that contains an icy drink. Air conditioners have condensate pans to catch this moisture and drainage lines to allow it to flow safely out of your home. You will occasionally hear water dripping into the condensate pan. You should only be concerned about the sound of water if it is happening very frequently or constantly, or sounds more like a trickle than just a drip, because that can be a sign of a refrigerant leak.


At the end of a cooling cycle, when the compressor shuts down, there may be a clicking sound from the mechanical parts, like the fan motor, stopping. However, clicking that happens throughout the cycle can indicate an electrical issue, so you should pay attention to when you’re hearing the sound and get air conditioning repair in Eveleth, MN if necessary.


The ductwork your conditioned air flows through experiences dramatic shifts in temperature. This can lead to expansion and contraction as cycles begin and end, and that can make a rattling sound that will not last long. If the rattling happens throughout the cycles, is very loud, or has gotten worse, there may be something loose in your ductwork that needs repair.

If you’re unsure whether the sound you’re hearing is a sign of an AC problem, we’d be happy to talk it over with you.

Reach out to Mesaba Heating & Air Conditioning today. Service to you is success to us!

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