Heat Pump Making Noise? Normal Sounds vs Warning Signs
How to tell a healthy winter whoosh from a grinding or buzzing unit, what to check safely and when to call.
The short answer: A heat pump making noise in winter is often just doing its job. A whoosh with steam, a click, a steady hum, a soft gurgle and a fan that stops and restarts are normal. Grinding, rattling, loud buzzing, screeching or banging are not. Clear snow by hand or with a soft brush, check the filter, and if a warning sound continues, set the thermostat to Off and call.
The first cold snap is when most people really start to hear their heat pump making noise. The outdoor unit works harder as the temperature drops and runs cycles you may not have noticed in the fall. Most of those sounds are harmless. A few warn that a part is wearing out or that ice is building where it should not.
This guide for Ontario and GTA homeowners sorts normal sounds from warning signs and lists the checks you can do safely. If something already sounds wrong, you can book a service visit online or call 310-HEAT any time, day or night.
Heat Pump Making Noise? First, Find Where the Sound Comes From
A central air source heat pump has two halves. The outdoor unit holds the compressor, coil and fan. The indoor unit is an air handler or, in a dual fuel home, your furnace with a coil on top. Stand near each one before you decide anything.
Outdoor unit
- Compressor hum and fan whir while heating
- Whoosh, click and steam during defrost
- Fan stopping, then restarting
- Warning signs: grinding, banging
Indoor unit
- Blower rush when heating starts
- Soft gurgle from refrigerant in the coil
- Clicks as backup heat switches on or off
- Warning signs: rattling, whistling
Note when the sound happens, and record a short phone clip. New to the equipment? Our guide to what a heat pump is and how it works explains each part.
Normal Winter Sounds, Step by Step
The easiest way to judge a heat pump making noise is to follow one heating cycle on a frosty day. Every step is normal.
1Start-up: a click and a rising hum
A relay clicks, the compressor starts with a low hum and the fan spins up. On very cold days it sounds busier. That is expected.
2Heating: steady whir and a soft gurgle
You hear the fan and an even compressor sound. A light gurgle from the lines or indoor coil is refrigerant moving, usually loudest just after start-up or defrost.
3Defrost begins: a click, a whoosh and silence from the fan
When frost builds on the outdoor coil, the reversing valve briefly switches the system into cooling mode. Natural Resources Canada (NRCan) explains that this sends hot gas to the coil to melt the frost while the outdoor fan shuts off. You hear a click, then a whoosh.
4Defrost ends: a second whoosh, steam and a fan restart
The valve switches back with a second whoosh, the fan restarts and steam may rise from the unit. Dripping and light crackling as ice lets go are normal too.
Is your heat pump making noise that matches these steps? Then there is nothing to fix.
How long and how often defrost should run is covered in our guide to heat pump defrost mode. Clicks indoors during defrost or deep cold are often backup heat; see our guide to heat pump emergency heat.
Warning Sounds: When a Heat Pump Making Noise Needs Attention
None of these sounds belong in a normal cycle. Match what you hear to a card and follow its advice.
Turn it off and call
Grinding
Metal on metal, often worn motor bearings. Running it longer can turn a small repair into a big one.
Turn it off and call
Loud buzzing
A harsh buzz, especially with the fan not turning, usually points to a failing electrical part. Do not open the unit.
Turn it off and call
Screeching or squealing
Often a failing motor bearing or a compressor under strain.
Turn it off and call
Banging or clanking
A loose or broken part, or fan blades striking built-up ice.
Safe check, then book
Rattling
Debris on the fan grille or a loose panel. If clearing debris does not help, book a visit.
Book a visit soon
Constant hissing or bubbling
A hiss that never stops, outside of defrost, can point to a refrigerant leak.
Refrigerant leaks need a licensed technician; our guide on how to detect refrigerant leaks lists the other signs. If the unit also blows cool air or will not start, see the three most common heat pump problems.
Smoke, sparks or a burning smell are not steam. Set the thermostat to Off, stay away and call 911 if there is any sign of fire.
Safe Checks for a Heat Pump Making Noise: Do and Don't
Set the thermostat to Off first so the fan cannot start while your hands are close. The U.S. Department of Energy also advises clearing clutter from around the outdoor unit with the fan's power off.
Do
- Clear snow by hand or with a soft brush from the top, sides and base.
- Remove leaves, sticks and debris from outside the grille.
- Check that the unit sits level. A sunken pad or stand can cause vibration.
- Look for roof drips that freeze on top of the unit.
- Check the indoor filter. NRCan recommends changing or cleaning it every three months.
- Open all registers so the blower is not straining.
Don't
- Don't pour hot water on the unit. It can refreeze deeper inside.
- Don't chip or scrape ice. Coil fins puncture easily.
- Don't shovel or blow snow onto the unit.
- Don't remove panels or touch wiring, the disconnect or refrigerant lines.
- Don't lift or re-level the unit yourself.
- Don't cover a running unit to quiet it.
Then set the thermostat back to Heat and listen through one cycle. If the warning sound remains, turn it off and call. Our furnace filter guide covers sizes, and our cold weather heat pump guide has more seasonal tips.
Heat Pump or Furnace? Sorting Out Dual Fuel Noises
Many GTA homes pair a heat pump with a gas furnace. The furnace takes over in deep cold or during defrost, so an indoor sound may not be a heat pump making noise at all. A boom at burner start-up or a squeal from the blower belongs to the furnace, and our guide to a furnace making noise decodes those sounds.
If you ever smell rotten eggs near a gas furnace, do not touch the thermostat or any switch. Leave the home, then call Enbridge Gas at 1-866-763-5427 or 911 from outside.
Heat Pump Making Noise but Working Fine?
Sometimes nothing is broken, but the sound still bothers you. Natural Resources Canada notes that most heat pumps have a sound rating of 76 dB or lower. Age, a loose stand or a spot below a bedroom window can make a unit seem louder than it should.
A technician can check the pads and stand. If your unit is near the end of its life, a newer cold climate model is often quieter, and qualifying models can earn a rebate through the Home Renovation Savings Program; check saveonenergy.ca for current amounts. Explore our heat pump installation and service options, or ask about a free Total Home Assessment, financing and our 10-year worry-free warranty.
When to Call About a Heat Pump Making Noise
Is your heat pump making noise that does not match the normal cycle? Answer these questions in order. The first "yes" tells you what to do.
Is there smoke, a burning smell, sparks or a gas smell?
Yes: leave and call 911, or Enbridge Gas from outside for a gas smell.
Do you hear grinding, screeching, loud buzzing or banging?
Yes: set the thermostat to Off and call a technician now.
Is thick ice covering the coil or touching the fan?
Yes: turn it off, leave the ice alone and book a repair.
Is there rattling or hissing that safe checks did not fix?
Yes: book a visit within a day or two.
None of the above?
It is most likely normal. Mention it at your next tune-up.
Motors, electrical parts, compressors and refrigerant are technician work; the Electrical Safety Authority warns that poor electrical work can cause shocks or fires. Our heat pump repair guide explains what a visit includes, and NRCan recommends yearly maintenance by a qualified contractor. Members of our maintenance and protection plans get that visit plus priority booking.
Heat Pump Help Across Markham, Richmond Hill and the GTA
Aire One has served Ontario homes since 1990 and holds a 4.8-star Google rating from 541 reviews. Our technicians are on call 24/7 to track down a heat pump making noise and to repair heat pumps of every make. Learn more about our HVAC company in Markham, our HVAC company in Richmond Hill and our full range of heat pump services.
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Frequently Asked Questions
Why is my heat pump making noise only in winter?
In winter the compressor works harder, and defrost cycles bring a click, a whoosh, steam and a pause from the fan. These sounds are normal. Grinding, banging or loud buzzing are not.
Is a whooshing sound with steam a problem?
Usually not. It is the defrost cycle melting frost from the outdoor coil. Call a technician if it repeats every few minutes or comes with thick ice that never melts.
Can ice cause a heat pump to make a scraping or banging noise?
Yes. Ice built up inside the unit or around the base can hit the fan blades. Set the thermostat to Off, clear loose snow by hand or with a soft brush, and leave the ice alone. Never chip it or pour hot water on it. Then call a technician.
Should I keep running a heat pump making noise like grinding or screeching?
No. Grinding and screeching usually mean a failing motor bearing or a compressor under strain. Set the thermostat to Off and call. In a dual fuel home, the furnace may be able to carry the heat until the repair.
How loud should a heat pump be?
Natural Resources Canada says most heat pumps have a sound rating of 76 dB or lower. A healthy unit gives a steady hum and fan whir. If it sounds much louder than it used to, have it checked.
Sources and Helpful Resources
- Natural Resources Canada: Heating and Cooling With a Heat Pump
- U.S. Department of Energy: Operating and Maintaining Your Heat Pump
- Electrical Safety Authority: Hire a Licensed Electrical Contractor
- Save on Energy: Home Renovation Savings Program
Matthew leads the Aire One Markham and Metro Toronto team, helping homeowners keep heat pumps and furnaces running safely all winter. Aire One has been a TSSA-registered, Carrier Factory Authorized Dealer since 1990.