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Why Is My Heat Pump Making Noises?

Heat pumps are durable and reliable HVAC systems that can be used with your furnace or as a stand-alone heating and cooling system.

Because heat pumps are large HVAC systems that carry out many mechanical processes at one time, they will make loud noises that are natural and common. But if there is a problem inside your unit, it will also make particularly frequent, loud, and unpleasant sounds.

How Does a Heat Pump Work?

A heat pump is a type of air conditioning system that can run in two directions. During warm months operates like a traditional air conditioner by removing warm air from inside your house and transferring it back outside. The major difference comes during the cold months when your heat pump will extract heat energy from outside air (yes, heat energy exists even in cold air) and transfer it inside your home. This process of heating a home is significantly more efficient than that of an electric system.

Heat Pump Descriptive Graphic

Heat pumps use many of the same components as an air conditioner, including refrigerants, coils, compressors, and fans. And like any hard-working machine with many complex parts, a heat pump will make its fair share of audible noises. Here are some common and some concerning noises you may hear from your heat pump:

Common Heat Pump Sounds

Humming or Buzzing

A low, constant humming or buzzing noise inside your heat pump is usually the sound of an electrical current running through the components. Coils, motors, and other components that require electricity to function have a constant current running through them.

If the humming or buzzing is obnoxious or louder than usual, you might need a heat pump repair and should have a professional technician inspect your system.


A swooshing sound is usually due to air or pressure release. For a heat pump, you’ll hear a swooshing sound when the outdoor unit of your heat pump is in defrost mode. Defrost mode protects components from freezing, so you’ll hear it at times in the winter. The swooshing sound occurs at the end of the defrost cycle as the air pressure releases and the fan turns on again for normal cycling.

When a heat pump enters defrost mode, it will also make a loud, low humming sound. This sound, along with the swooshing of air pressure release, are both normal, and you’ll hear them more frequently in the winter.

Startup and Shutdown Noises

Like any machine, when a heat pump turns on and off, it will make a sequence of natural — and sometimes loud — noises. A significant amount of power is required for the initial kick-on of a complex machine. Therefore, a loud rumble followed by the clicks and clanks of components starting and electricity flowing is normal when your heat pump shuts on and off or when it kicks into defrost mode.

If these noises become noticeably louder or you notice your heat pump is turning on and off frequently, it never hurts to have a routine inspection by an HVAC professional to make sure your system is functioning properly.

Sounds That Indicate You Need Professional Service

Banging or Rattling

Rattling noises could indicate loose bolts and panels that need to be tightened, which can be prevented or taken care of with routine maintenance. A banging noise could be the fan blade hitting debris that got inside the unit. Both of these issues are generally low-risk if taken care of quickly.

If banging or rattling noises are exceptionally loud and/or persist after bolts are checked and debris is clear, then you’ll need a professional technician to inspect your heat pump.


A gurgling sound likely means your heat pump is low on coolant or leaking coolant and should be serviced immediately. Whether it’s the coolant level or another issue causing the noise, you’ll want a professional HVAC technician to diagnose a gurgling sound coming from your heat pump.

Metal-on-Metal, Squealing, and Screeching

You should have screeching, squealing, or metal-on-metal sounds professionally inspected right away. These sounds could be caused by several issues, such as your fan blade hitting an internal component or hot gas going through the valves.

It’s best to turn off your unit right away to prevent further damage and wait for an HVAC technician to inspect it before turning it back on.  

When To Call for Professional Heat Pump Service

Any machine will make some noise just from being turned on and functioning normally. When you hear noises that are unfamiliar, louder than normal, or alarming, you should turn off your heat pump and call AirCo for a heat pump repair. We also offer heat pump maintenance to prevent unnecessary wear and tear on your system. 

Call 817-591-1225 or contact AirCo online for reliable heat pump services in the Dallas-Fort Worth area.

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