April 6, 2021
Carrier Heat Pump

Have you ever listened to your air conditioner to notice what sounds it makes? Hopefully, it does not make much noise, but if it does, your system may have run into a problem. If you pay close attention to the sound and its source, you may be able to determine what is wrong.

You likely are not going to fix most problems yourself, but you can get a sense of the cost, and accelerate the diagnosis. Here are some of the noises you may want to listen for that could spell trouble.


You may expect to hear screaming from a toddler or in a horror movie, but not from your air conditioner. If you do hear a screaming sound, you may have a dangerous refrigerant leak. If you hear a screaming sound from your system, turn it off, and call a technician to find the source.

Did the screaming from the indoor part of your unit? Consider cracking some windows to help ventilate any refrigerant in your air.


Your system may have some minor humming as it runs. However, it could also indicate some problems like loose parts or the refrigerant piping vibrating. It may also indicate electrical issues or a fan motor getting ready to give out. Humming could also be caused by other electrical problems in your system.


You are likely going to hear buzzing coming from outside your house if there is a problem. This can come from the capacitor in the condensing unit. The capacitor stores a large charge to jump-start the compressor motor and condensing fan. This may also be accompanied by warm air as the AC is running.


Another common sound air conditioners make as they age is a rattle. This most strongly indicates something is loose and needs to be tightened. At your condensing fan, it could be the blades coming loose, or even the cage on top of the condenser loosening. Inside, it could be clogged air filters. Start by checking to make sure there is no debris caught in or near the fans, including twigs at the outside unit.


Occasionally, your outdoor condensing unit may sound like the whirring of a helicopter. If this is the case, it likely is the blades on the condensing fan coming loose and needing to be tightened. While the actual job is quite easy, be sure to disconnect the power to the unit before attempting the job.


Your system may sound normally have a little humming, but you want to investigate to make sure you know what it is. This is especially important if it is a new humming you are noticing.

Sometimes, humming can be caused by the vibration of the refrigerant lines or parts coming loose. Left uncorrected, these can lead to major repairs and expenses.

A louder, intense hum is likely caused by a daily electrical component, like a capacitor, and it daily to charge properly. This is a relatively easy fix for a trained professional but leads to major repairs if uncorrected.


Your system will likely have a series of clicking sounds as it cycles on and off normally. This is caused by various relays and contactors activating while cycling.

However, if the clicking is constant, or repetitive for the entire cycle, you likely have a failing component. One of the more common components to fail that makes this is sound is the contactor in the condensing unit. This part acts as the switch to turn the unit on and off as the system cycles. If you hear constant or repetitive clicking, it is signaling to turn the condenser on and off, which is hard on the condenser motor.

Banging and Clanking

Banging and clanking are indicators of loose or broken parts or debris caught in the system. Your annual maintenance will ensure your system is free from such debris. The parts that could cause this includes loose fan blades, a broken fan crankshaft, a piston pin, or a connecting rod. It could also indicate your fan is out of balance.

Annual maintenance and quick repairs when you have a problem are the quickest ways to keep your repair costs down. Climate Control has been the trusted name in AC repair and maintenance since 1989. We go beyond air conditioning, and also heating and water heater installation, maintenance, and repair. Call to schedule your air conditioning service call with one of our expert technicians in Portland today.

company icon