Is It Normal to Have a Noisy Heat Pump? - Parker & Sons Skip to content

Is It Normal to Have a Noisy Heat Pump?

A woman trying to block out loud noises with a pillow

A heat pump can often be a noisy system. But when is yourunit just being loud, and when does the noise indicate a bigger problem?


First of all, it helps to know how a heat pump works. As you may know, a heat pump has both an outside and inside unit, with the outside being almost exactly like an A/C.

In fact, the only difference between a heat pump and an A/Cunit is that the heat pump contains a valve that changes the flow of yourrefrigerant, and makes it condense inside your home instead of outside. Now,heat is released inside your home.

But what happens when the valve switches? A whole bunch ofnoise happens, that’s what!

Normally, your heat pump outdoor unit will be blowing coldair out of the fan on the top. However, you may want to put your heat pump indefrost mode so that you can clear up any frost that’s collected on the coil.

When the heat pump goes into defrost mode, you’ll hear aloud, low hum, like the low note of a trumpet! You’ll feel heat instead of coldcoming out of the top, and the fan will no longer be running. You may even seesteam! All of this is normal, because the system is defrosting the ice off thecoils.

Then, when your system exits the defrost cycle, you’ll heara loud noise of air pressure being released, and you’ll hear the fan comingback on again.

Another common heat pump noise in the winter is from theunit turning on or off.

The compressor will usually be quite noisy, because itswhole job is to compress air and refrigerant. The most common type ofcompressor, a scroll compressor, is quieter than the other type of compressor,a reciprocating compressor (because that type uses loud pistons).

The scroll compressor type of heat pump is more efficient and reliable, and we recommend you install that type, because repairs are cheaper, too! But this type of compressor still makes noise when pumping refrigerant, and when it turns off, the air pressure taking a moment to equalize can cause loud “blowing” noises!

Similarly, if the heat pump’s outdoor unit is turned off, but you still hear a low buzzing noise, that’s because of the solenoid coil on the valve. The buzzing comes from the low voltage electricity of the coil, and is constant.


So then, what noises aren’t normal?

If you hear a loud squealing noise, that’s hot gas goingthrough the valve, and it means that your system needs a discharge valve!

Or, if it’s not a buzzing or droning you hear…but more ofa clanking…then it’s likely your fan blades are hitting another internalcomponent.

In winter, it’s possible that ice is stuck in your blades,too. You’ll want to turn the unit off right away. The fan blades hittingsomething could unfortunately do a lot of damage, and cause a hole in thetubing, making refrigerant leak everywhere!

Overall, a somewhat noisy heat pump is just the reality ofthe system. However, it should really only be loud during defrost mode, or ifyou have a reciprocating compressor instead of a scroll compressor.

But there are other culprits that could cause a noisy heatpump too: a malfunctioning reversing valve, not enough refrigerant, or a badmotor.

These aren’t issues you can fix on your own, so if you can’t easily diagnose and fix the problem just by looking at it, then call one of our professionals.


We’ll shush that noisy heat pump! Schedule an appointment or call 602-273-7247.

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