Coronavirus (COVID-19) Update- Garrison & Garrison continues to practice all safety precautions laid out by the CDC with regards to COVID-19. The safety of our customers and staff is our #1 priority. Review our full disclosure: Garrison & Garrison COVID-19 Safety Precautions

Why is my Indoor HVAC Unit Making That Noise?

Why is my Indoor HVAC Unit Making That Noise?

It’s not uncommon to hear noises coming from your indoor unit or furnace, but that doesn’t mean it is any less scary when you hear it. You might fear that it signals a costly repair or the untimely breakdown of your unit. This guide will help you pinpoint where the issue may be coming from and if the noise is something to worry about.


Loud scraping or metal hitting metal sound

Let’s just start off with the worst of the bunch. If you hear a loud scraping or metal hitting metal sound coming from your indoor HVAC unit or furnace turn off your unit and call us in immediately! There are a few reasons you might be hearing this sound and none of them are great. From best to worst let’s start with a loose blower wheel.

Lose Blower Wheel

The best case scenarios is that your blower wheel came loose from the motor shaft and is hitting the blower housing. If you managed to catch it early and there is no damage, the blower wheel can be put back in place and tightened. If the blower wheel is broken, you’ll know right away. The sound is awful, like nails scratching a chalkboard! In this case, the piece will have to be replaced. In the worst case scenario, your motor mount is broken, and it’s caused the entire motor and blower assembly to drop, which then causes the blower wheel to keep hitting its housing. No matter which scenario it is, it’s best to turn off that unit and call us in. Leaving it running might make the situation worse and cause the repair bill to rise.


Loud Pop or Banging Sound

You’re most likely to hear this when the system fan first starts or stops, and if you have sheet metal ductwork.  When the fan starts, the pressure from the fan could cause the ductwork to pop in. So when the fan stops, the pressure is released and the ductwork pops back out. This could indicate ductwork that is too small for your house, a clogged filter, closed vents, or a flimsy duct. Start with what you can address yourself. Change the air filter if it’s dirty, and open your vents if they are closed. If you still hear the sound afterwards, go ahead and give us a call.

Loud, humming noise

If you hear a loud, humming noise coming from your indoor unit, but it otherwise seems like it’s working just fine, then you might not have anything to worry about. Some transformers are noisier than others and this can simply be a sign of a noisy one. If you hear the loud, humming noise and your indoor unit is not working well, it can be a sign of a bad indoor fan motor or capacitor.


Loud thumping or vibrating sound

This is basically the sound your washer would make if you put some shoes in there or if your washing machine is out of balance. Just like your washer, a loud thumping or vibrating sound coming from your HVAC can be a sign of an out-of-balance indoor unit. While it’s certainly not the most grating noise on the list, it shouldn’t be ignored. Like most things, early detection and treatment will keep other issues from developing.


Rattling or High-pitched sounds

You’ll typically hear these noises coming from a heat pump. This may not be a sign for anything serious. Some heat pumps just have noisy check valves or metering devices, and it’s likely just related to the refrigerant flow. Check the air filter, and change it if it’s dirty. If the sounds grows louder and becomes annoying even after changing the air filter, give us a call.

Call Us for Service

No matter what the noise is, if it’s making you uneasy or it’s grown to be a nuisance, give us a call. It’s always better to be safe than sorry and those small noises you ignore could grow to be huge repair bills. We offer 24/7 maintenance to the Huntsville and Madison County area for all your HVAC service needs. Garrison and Garrison Heating and Cooling has been serving the HVAC needs of the Tennessee Valley for more than 45 years, and we’re still going strong.