Heat Pump Making Noise? What Each Sound Means and What to Do
Heat Pump Making Noise? What Each Sound Means and What to Do
Ben Amina
Aire One East Heating & Cooling, 1910 Dundas St E #117, Whitby
A heat pump making noise is one of the most common winter calls we get from Durham Region homeowners. The good news is that many heat pump sounds are perfectly normal. A heat pump switches between heating and defrost, runs its outdoor fan at different speeds, and moves refrigerant through its coils, and each of those jobs makes a sound. Other noises, like grinding, screeching, or loud banging, are early warnings that a part is wearing out or something has come loose. Knowing the difference can save you an unnecessary service call, or catch a small problem before it becomes a breakdown on the coldest night of the year. This guide goes through nine sounds, explains what each one means, and tells you what you can safely check yourself.
- A whoosh, hiss, or burst of steam from the outdoor unit in winter is usually the normal defrost cycle.
- A single click or clunk when the heat pump starts, stops, or switches modes is normal.
- Grinding, screeching, or squealing often points to a worn fan motor or bearing.
- Rattling is often loose panels, screws, or debris, while loud buzzing can be an electrical part.
- Turn the system off and call a technician for grinding, banging, or burning smells.
Short answer: A heat pump making noise is not always a problem. Whooshing, hissing, steam, and a click when it switches modes are normal parts of winter operation. Grinding, screeching, loud buzzing, banging, or rattling that keeps getting worse point to a mechanical or electrical problem that a licensed technician should check.
Aire One East diagnoses heat pump noises across Durham Region, including nights and weekends. Call 905-576-7600.
Normal sounds a heat pump makes
Before you worry about a heat pump making noise, listen for these three normal sounds:
- 1. Whooshing or hissing with steam. In winter, frost builds on the outdoor coil. The heat pump reverses briefly to melt it, and you may hear a whoosh, see steam, and notice the outdoor fan stop for a few minutes. Our heat pump defrost mode guide explains this cycle.
- 2. A click or clunk at start and stop. The reversing valve and electrical contactor switch on and off as the system changes modes. A single click is normal.
- 3. Gurgling or a soft hum. Refrigerant moving through the lines can gurgle, and the compressor gives off a low, steady hum while it runs.
Heat pump making noise that needs attention
If you hear a heat pump making noise like one of these six sounds, something needs a closer look:
- 4. Grinding. Often a worn motor bearing in the outdoor fan or the indoor blower. Grinding gets worse over time and can lead to a seized motor.
- 5. Screeching or squealing. Can come from a failing fan motor, a dry bearing, or high pressure inside the compressor. Turn the system off if it is loud and constant.
- 6. Rattling. Loose access panels, screws, or a fan guard, or debris such as twigs and ice inside the outdoor unit.
- 7. Loud buzzing. A buzz that is louder than the normal hum can point to a failing contactor, capacitor, or another electrical part.
- 8. Banging or clanking. A loose or broken part, or a fan blade striking ice or the fan guard.
- 9. Constant loud humming with no fan. The motor is getting power but cannot start, often because of a failed capacitor.
Heat pump making noise outside in winter
Winter is when most people first notice a heat pump making noise outdoors. Ice building up around the base of the outdoor unit or dripping from the roof can reach the fan, causing a scraping or banging noise. Snow drifts against the coil make the heat pump work harder and defrost more often, which means more whooshing. Keep at least 30 centimetres clear around the unit and make sure roof runoff is not dripping on top of it. Our heat pump extreme weather guide has more winter tips.
Heat pump making noise inside the house
When you hear a heat pump making noise inside, it usually comes from the air handler or, in a ductless system, the wall unit. A rattling or whistling from vents can be a dirty or bent filter, a closed register, or loose ductwork. A clicking from a ductless wall unit is often plastic expanding and contracting as it warms up. A dripping or gurgling sound can mean the condensate drain is partly blocked. Check and replace the filter first, as explained in our furnace filter guide, and keep supply and return vents open.
What to check before you call
- Look at the outdoor unit for ice, snow, twigs, or leaves and clear them gently by hand or with a soft brush.
- Check that the access panels are on and the screws are snug.
- Replace a dirty filter and make sure vents are open.
- Note when you hear the heat pump making noise: at start up, during defrost, or all the time. That helps the technician find the cause faster.
- If the heat pump also stops heating, our heat pump not working guide covers the next checks.
When a heat pump making noise needs a technician
Call a licensed technician if the heat pump is grinding, screeching, banging, or buzzing loudly, if you smell burning, or if the noise is getting worse. Motors, capacitors, contactors, and refrigerant are all jobs for a professional. If the outdoor unit is damaged and the house is getting cold, switch the thermostat to emergency heat while you wait, as explained in our heat pump emergency heat guide.
Our team handles heat pump repair across Durham Region, and annual heat pump maintenance catches worn bearings and weak capacitors before they fail.
Key terms in this article
- Defrost cycle: a short cycle that melts frost from the outdoor coil in winter
- Reversing valve: the valve that switches a heat pump between heating, cooling, and defrost
- Contactor: an electrical switch that turns the outdoor unit on and off
- Capacitor: a part that gives motors the boost they need to start
- Compressor: the pump that moves refrigerant through the system
- Air handler: the indoor unit that holds the blower and coil
Frequently asked questions
| Your heat pump making noise questions, answered |
|---|
| Why is my heat pump making a whooshing noise in winter? A whoosh or hiss, often with steam, is usually the defrost cycle. The heat pump reverses briefly to melt frost from the outdoor coil, then returns to heating. It is normal. |
| Is it normal for a heat pump to click? Yes. A single click or clunk when the heat pump starts, stops, or switches modes comes from the reversing valve and contactor. Repeated rapid clicking without the unit starting should be checked. |
| Why is my heat pump making a grinding noise? Grinding usually means a worn bearing in the outdoor fan motor or indoor blower motor. Turn the system off and call a technician before the motor seizes. |
| Why is my outdoor heat pump unit rattling? Rattling often comes from loose panels or screws, debris inside the unit, or ice touching the fan. Turn off the power and check for debris, then call a technician if it continues. |
| When should I call someone about a heat pump making noise? Call a licensed technician for grinding, screeching, loud buzzing, banging, or any burning smell, or if the heat pump stops heating. |
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References and further reading
