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The heat pump next to the building makes a loud noise when it shuts off

A heat pump that makes a loud noise when it shuts off can indicate several different problems. Some of the problems may not indicate a serious issue, while others may require you to call an HVAC professional.

Regardless of the issue, it is important that you address the problem as soon as possible. The more you wait to resolve a heat pump making loud noises, the worse the problems will become.

The following are some reasons that your heat pump may be making loud noises when it shuts off.

Rattling Ducts

The rattling noise that your heat pump makes when it shuts off is caused by the ducts. They are usually made of metal and are flexible, so they can be folded or bent without breaking.

When you turn off your heat pump, the fan stops spinning, and air continues to flow through the ducts. This causes them to vibrate against each other and make a rattling sound. If you hear this noise often, it could mean one of three things:

  1. Your ductwork may be loose or damaged. This can cause air leaks that cause your unit to work harder than necessary and run longer than expected.
  2. Your ductwork might not be insulated properly, allowing cold air from outside to enter through cracks in your insulation.
  3. If there isn’t enough space between pipes or ducts (such as when they’re too close together), this can also cause rattling noises as well as reduce airflow efficiency.

If you experience any of these problems, you should call a professional immediately. If left untreated, this can lead to more serious issues like damage to your ductwork.

Loose Blower Fan or Fan Belt

If your heat pump makes loud noise when stopping, it could be because the blower fan is loose or has a worn-out or broken belt. This is common in older heat pumps and can be fixed by tightening the fan or replacing the belt.

Worn Compressor

A compressor is what pumps the refrigerant through the system to transfer heat from outside air into your home. It’s also what pumps the refrigerant back outside when your heat pump switches from heating mode to cooling mode.

The compressor is a little like a car engine: it runs constantly except in sleep mode when it idles briefly before shutting off completely.

However, if the springs which support the internal components of the compressor are worn out, the compressor can make a loud noise when it shuts off.

This is because there’s no longer enough support for the internal components, and they slam into each other when they stop moving. In such a case, you would need to replace the compressor.

Water in the System

If you hear a loud noise when the heat pump shuts off, it may be because of water in the system. Water in your heat pump’s system can cause a compressor to overheat and break down.

This is especially likely if there’s a leak in your ductwork or drain line, as well as other problems that lead to condensation. If these things happen, they’ll result in water building up in your air handler or furnace unit and blowing out of its vents when it shuts off. A loud bang followed by an annoying gurgling sound is what we’re talking about here.

The good news is that you can fix this problem by draining the system and drying it out. This will help prevent condensation from building up again in the future, which should eliminate the loud noises as well.

Common Noises a Bad Heat Pump Produces

Heat pump at building facade making common noises

Heat pumps are mechanical devices that move heat from one location to another. When it’s working properly, you shouldn’t hear much at all.

However, if something goes wrong with your unit and you start hearing strange noises coming from your heater or air conditioner, don’t panic. It may just be a sign that it needs servicing or repair work done.

Some common noises heat pumps produce include:

Metal to Metal Sounds

One common noise a heat pump makes is metal-to-metal sounds. That’s because the equipment is made up of many moving parts, which can cause these noises. There are a few possible causes for this, but none of them are dangerous to your system.

One cause is that the fan blade has become too loose and it’s hitting the frame or another part. You can adjust this by tightening the screws on either side of the blade with a wrench.

Another cause for metal-to-metal sounds could be that there’s a problem with your blower wheel. If you hear strange noises coming from your unit when it’s running, this could be what’s causing them.

The blower wheel is responsible for pushing air through the system. However, if it becomes damaged or warped, it will not be able to do its job properly and may make these kinds of noises. It can also cause other issues like overheating, which can cause damage to other parts.

Gurgling Sounds

If you hear gurgling noises from your heat pump, it may be experiencing a refrigerant leak. Leaks can be caused by faulty valves or seals, which allow refrigerant to escape into the air around your home. If not remedied, this may cause mold to grow on the outside of your unit and damage other parts of the system as well.

Banging Sounds

If you hear banging or clanging sounds from your heat pump, it may be due to loose parts. This could mean that the unit has been installed incorrectly or that some of the components are damaged.

Vibrating Like Noises

Vibrating noises can be caused by loose parts or a faulty compressor. A defective fan motor can also cause vibrations and make your unit vibrate at times.

Buzzing Sounds

Buzzing or humming sounds are usually caused by a faulty motor. This can mean that the motor is worn out and needs to be replaced.

Hissing Sounds

Hissing sounds can be caused by several different things. If there is a leak in your system, it may emit a hissing sound as the cold air escapes from the leak. A frozen expansion valve can also cause hissing sounds as it expands and contracts with changes in temperature.

How To Quiet a Noisy Heat Pump?

The sound of a heat pump can be distracting, but there are some things you can try to make it quieter. Here are some tips and tricks to quiet down your heat pump:

Check the Grille

The grille is the cover over the outside of your unit. It’s designed to keep insects, leaves and other debris out of your heat pump so it can operate properly. However, this can also cause some noise problems if it isn’t properly installed or adjusted correctly.

Clear Debris

If there’s a lot of debris clogging up your unit, it could be causing the fan to work harder than it needs to in order to circulate air through the system. This will make the unit louder. Make sure you clean out any leaves or other debris that may have accumulated around your heat pump so it can run as efficiently as possible.

Tighten the Mounting Bolts

If your unit is not properly secured, it will make noise as it vibrates against the mounting bracket. You can usually tell if this is the issue because the problem is only noticeable when the unit is in operation. A quick fix for this problem is to tighten the mounting bolts that hold your heat pump in place.

Ensure Proper Refrigerant Levels

Refrigerant is what keeps your heat pump running smoothly and efficiently. If there is not enough in the system, it can make a loud noise as it struggles to cool or heat your home.

You can check the levels of refrigerant yourself by locating an access point on the outside of your unit. The access point will be clearly labelled with instructions on how to open and repair it if necessary.

Check Your Outdoor Unit’s Fan Blades

Heat pumps have a fan that draws in cool air from outside and circulates it around your home. The fan blades on this unit can become damaged or bent over time, which can cause a loud noise when the unit is operating. If you notice any damage to your outdoor unit’s fan blades, contact an HVAC technician for repairs.

Use a Sound Blanket Wrap

A sound blanket wrap is an insulating material that can be applied to your unit to help reduce the amount of noise it makes. These blankets are made from a special type of foam that can be cut and shaped to fit your air conditioner perfectly. Some models even come with Velcro attachments so you can easily attach them in place when finished.


Your heat pump may make a loud noise when it shuts off, but that’s not necessarily a sign of a problem. If the noise becomes louder or more frequent and continues to happen even after the heat pump shuts off, then you might need to call in a professional like Meadow Air to have your heat pump inspected.

We encourage you to check out our HVAC blog for more tips and helpful information regarding heating and cooling systems.

Call us today for more information! 602-812-0648