While most HVAC units are now designed to be silent, it’s not uncommon to hear an occasional ding or swoosh. However, when those occasional pings or bangs become louder and more frequent, it could be a sign that your unit needs to be serviced. If you’re not sure what’s normal and what’s not, here are five noises you should never ignore from your AC.

1. Clicking

Although not typically considered an issue, clicking sounds could indicate a defective thermostat. Depending on the make and model, some HVAC systems will click when they kick on and off. However, ongoing clicking isn’t normal and could mean the electrical system needs repair.

The owner’s manual might have some troubleshooting ideas to stop the clicking, but if it doesn’t or if they don’t work, don’t try to fix it yourself. Play it safe and call an air conditioning professional.

2. Squeaking

Squeaks and squeals are cute when a baby makes them, but, it’s another story when your AC does. These types of noises are usually warning signs that your outdoor fan motor needs repair, or possible the blower wheel needs replaced.

The fan motor cools the refrigerant that cools the air that keeps your home at a comfortable temperature. The cost of replacing the fan motor is usually around $300 to $600. While that is a good chunk of money, you need to try to get it taken care of as soon as possible. Because the fan motor plays such a significant role in your AC, if it breaks then other, more expensive parts are probably also going to break too.

The blower wheel is what moves air through the ducts, pushing cool air into your home and pulling warm air into the AC unit to be cooled. When the wheel is dirty, the motor has to work harder to turn it, and it can wear out. Fixing it will usually on average be about $450. To prevent this problem from coming back in the future, be sure to switch out your air filter regularly.

3. Banging

Any type of banging sound coming from your unit needs immediate attention. It typically indicates a more serious issue, either with the air compressor or piston inside the unit. It could also mean that the crankshaft is going up, so time is of the essence. Because there are several things the problem could be, if you hear banging, schedule a service call as soon as possible. You may not have time to work through all the options on your own.

4. Rattling

Rattling noises can be indicative of both minor and major issues. Many times, the rattling sound is simply a loose screw or bolt, which is an easy fix. However, if the rattling is ongoing and continues to get louder over time, it could mean parts of your HVAC need replaced. It could also mean that there’s shrubbery or branches stuck in the outside compressor.

Do a quick check around your compressor and clear away any foliage that may be causing problems. Then do a basic check for loose screws. If that doesn’t help, call an HVAC professional to find and fix the problem.

5. Buzzing

Buzzing is another noise that your AC might make when something isn’t working properly. A soft humming sound is normal but if your system is continually buzzing or if it gradually gets louder, your system could be on the verge of freezing up. This is seen most often when the unit is run for too long without cycling properly.

Even if your system is brand new, you should never ignore sounds that are out of the ordinary. The worst, and possibly the most expensive, mistake you can make is ignoring any odd sounds your system continues to make. If you suspect your AC is malfunctioning, contact your HVAC technician for inspection and repair.


Anita Ginsburg

By Anita Ginsburg
who is a freelance writer and residing in Denver, CO. She studied at Colorado State University, and now writes articles about health, business, family and finance. A mother of two, she enjoys traveling with her family whenever she isn’t writing. If your air conditioning system is making odd noises, she recommends calling an air conditioning technician as soon as possible.

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