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Serving Katy, TX and the Surrounding Areas

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Serving Katy, TX and the Surrounding Areas
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AC Comfort Blog

The Sounds You SHOULD Hear From Your AC

woman-relaxingA common topic about air conditioners is the odd noises that warn of something wrong that may require repairs or basic troubleshooting. We’ve mentioned AC warning noises in several of our blogs.

What’s not talked about as often are the sounds an AC normally makes. These are the sounds you should expect to hear from your air conditioner as it operates. We’ve decided to make this post to tell you what you want to hear from your AC. This will make it easier to put strange noises in context—you’ll have a better idea what constitutes a warning sound.

The hum of the compressor

The most important noise you’ll hear from an air conditioner that indicates it’s performing its job as normal is when the compressor in the condenser cabinet starts to hum. This signals the start of the air conditioner’s cooling cycle. The AC has received a signal from the thermostat that the interior of the house requires cooling, and the compressor’s motor starts so it can put the liquid refrigerant under pressure and change it to a hot gas so it will circulate to carry out heat exchange. Once the compressor turns on, you can expect to feel cool air coming from the system. (If you don’t, the compressor may be malfunctioning.)

Fan blowing

This is the main sound you’ll hear your air conditioner make from the inside of the house: it’s the blower fan pushing air through the AC and then into the ductwork. It should be a gentle and steady sound, one that will turn into the white noise of the summer season.

The movement of water

This is a sound you’ll hear from the inside components of the AC. It isn’t constant, but something that you’ll hear at periodic intervals. If you’ve ever watched a window AC at work from the outside, you’ll notice water dripping from it. This is the same condensate moisture you hear from your central air conditioner, although the moisture isn’t dripping into your house but exiting to the outside through a drainage system. When you hear water from the AC, it’s the drainage system removing the moisture that collects along the evaporator coil.

The rattle of ducts

The ductwork exiting from the central HVAC cabinet is made from metal (the rest of the ductwork may be constructed of flexible plastic or ductboard). Metal changes shape as it’s heated and cooled, so when the air conditioner turns on, the metal may make a rattling noise. This won’t continue for long—and if it does, it often means the ductwork is loose.


When an AC finishes its cooling cycle, you’ll hear several clicking sounds coming from it. This is the standard sound of machinery stopping, such as the compressor and motors. Hearing clicking at other times can indicate trouble, such as failing capacitors or loose parts. Listen to your AC as it cycles down and you’ll become accustomed to what “normal” clicking sounds like. 

When you’ve got trouble noises, the best route is to reach out to our technicians for air conditioning repair in Katy, TX. We’ll keep you cool!

At AC Comfort, Your Comfort Is Our Business! If you hear AC noises you think you shouldn’t, call us for the repair work you need.

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