Why Is My Heat Pump Loud in Winter? Normal Sounds and Fixes

A heat pump loud in winter is usually doing something normal. Heat pumps work harder when it’s cold, and they defrost their outdoor coil several times a day. Both can make the system sound different from summer. Some sounds, though, point to ice, a loose part or a failing component. This guide helps you tell the difference and quiet things down.

Why is my heat pump loud in winter?

• They run longer and faster. Many modern heat pumps have variable-speed compressors that ramp up as it gets colder. More speed means more sound.
• Defrost cycles. Several times a day, the system reverses briefly to melt frost off the outdoor coil. That switch often makes a whoosh or hiss. Here’s what a normal defrost cycle looks like.
• Snow and ice. Ice on the fan guard or blades can cause scraping, thumping or vibration.
• Cold metal. Panels and brackets contract in the cold and can tick or creak when the unit starts and stops.

Natural Resources Canada (NRCan) notes that modern heat pumps are often quieter than traditional heating and air-conditioning systems. Read NRCan’s myths and facts about heat pumps. A heat pump that is suddenly loud in winter, or louder than it was last year, is still worth paying attention to.

Normal and abnormal heat pump sounds

Use this table if your heat pump is loud in winter and you’re not sure whether it needs attention.

Sound	Likely cause	Normal?
Steady hum	Compressor and fan running	Yes
Whoosh or hiss for a few seconds	Switching into or out of defrost	Yes
Gurgling or trickling	Refrigerant flow, or water draining during defrost	Yes
Light ticking or creaking	Metal expanding and contracting	Usually
Scraping or thumping	Fan hitting ice or snow	No: clear the unit safely
Rattling or clanking	Loose panel, screw or debris	No
Grinding or screeching	Worn fan motor or bearing	No: turn it off and call a technician
Loud buzzing that doesn’t stop	Possible electrical problem	No: call a technician

How to make a heat pump quieter

If your heat pump is loud in winter, start with the simple fixes:

1. Clear snow and ice. Gently remove snow from around and on top of the unit. Don’t chip ice from the coil or fan; the fins are easily damaged.
2. Check for loose parts. With the power off, look for loose panels or screws. Leave anything inside the cabinet to a technician.
3. Keep the base stable. A unit that isn’t level, or a stand that has shifted with frost, can vibrate. An installer can re-level it and add vibration isolators.
4. Ask about a quiet mode. Many models have a night or low-noise setting. It may reduce heating output, so ask your installer when it’s appropriate to use.
5. Book annual maintenance. NRCan recommends having a qualified contractor service your heat pump every year.

If the noise bothers you or your neighbours, the location may be the real issue. A unit mounted on a wall next to a bedroom, or in a narrow gap between houses, will sound louder. Talk to your installer before building an enclosure; screens must not block airflow. Our guide on how to hide a heat pump explains the trade-offs.

Choosing a quiet heat pump

If you’re buying a new system, compare the published sound rating in decibels (dB) for the outdoor unit. Lower is quieter. Also look for:

• a variable-speed (inverter) compressor, which runs smoothly at low speed most of the time
• a model that is correctly sized, because an undersized unit runs flat out more often (see our heat pump sizing guide)
• a location away from bedroom windows and your neighbour’s property line

Some municipalities have noise bylaws that apply to outdoor equipment. Check with your city or town if you’re unsure.

When to call a technician

• The noise is new, getting worse or happens all the time.
• You hear grinding, screeching, banging or continuous buzzing.
• The unit is covered in thick ice that doesn’t clear after defrosting.
• The system blows cold air for long periods in heating mode.

The bottom line

A heat pump loud in winter is often just working hard or defrosting. Clear snow, check for loose parts and book annual service. Call a professional for grinding, banging or persistent ice. If you’re planning a new installation, choosing the right size and location is the best way to keep it quiet.

Frequently asked questions