Is your heat pump not heating like it’s supposed to, and blowing cold air instead? Or relying on backup heat more than usual? Don’t panic—winter conditions can trigger issues that look serious but are often common problems that can be fixed in minutes with some easy steps. Canadian winters can be unforgiving. But your heat pump is designed to keep your home warm and comfortable no matter the weather outside. So before you book that service call, take a look at this simple heat pump troubleshooting guide containing steps that can restore comfort, prevent unnecessary electric heat pump costs, and keep your system running smoothly without interruptions this winter. Common Heat Pump Issues In Winter and How To Fix Them 1. Why is my heat pump blowing cold air? Is your heat pump suddenly doing the switcheroo and blowing cold air? In most cases when your heat pump is not heating, it’s typically due to one of these two reasons: Reason #1: Your System Is Set To The Wrong Mode If this is your first time owning a heat pump, you might not realize that in winter, you need to switch it from COOL (or AUTO) to HEAT mode so it can warm your home instead of blowing cold air. It’s always best to set your heat pump to HEAT mode instead of AUTO since the latter forces your system to continue switching between heating and cooling as it tries to regulate temperature, which can result in cool air blowing unexpectedly. How to set your heat pump to HEAT Mode: If you have a central ducted heat pump system: Press the MODE button on your thermostat or go to MODE on your thermostat display and select HEAT. If you have a ductless mini-split heat pump system: Pointing the remote at the indoor head unit, press the MODE button on your remote and set it to HEAT by selecting the sun icon. If you have a multi-zone system, you will need to repeat this for each indoor head. Reason #2: Your Heat Pump Is In Defrost Mode What is a defrost mode? When outdoor temperatures drop, frost or ice can build up on the condenser coil, causing the system to temporarily pause regular operation. During this period, the heat pump redirects energy to melt the ice instead of heating your home. This is called the defrost cycle. Because the system briefly reverses the heating process, the indoor unit blows cool air for a short period and your backup heating comes on. If you take a look at your condenser while it’s undergoing a defrost cycle, you’ll see steam and water coming from the unit. This is completely normal! What to do if the defrost mode is on: A defrost cycle typically lasts 5–15 minutes. Wait for it to end and your system should return to normal heating afterward. If the issue still persists, perform a hard reset by powering the system off at the electrical panel by flipping the breaker switch. Wait 20 minutes, and then turn your heat pump back on. Other Possible Reasons Your Heat Pump Is Blowing Cold Air: If none of the above resolves the issue: Your compressor might be malfunctioning Your refrigerant levels might be running low In these cases, it’s best to contact a qualified HVAC professional for inspection and service. 2. Why is my heat pump covered in ice? Is this normal? Why Your Heat Pump Freezes In Winter Canadians are no strangers to snow. During the winter, there are frequent freeze-thaw cycles, creating ideal conditions for ice and frost to form and build up around your heat pump’s outdoor unit. Even when snowfall is light, melting and refreezing can lead to ice accumulation over time and create issues for your heat pump in winter. If your outdoor condenser is installed directly under some rain gutters, the runoff from rainwater can drip onto the unit and freeze, gradually creating thick ice. Heavy icicles can form along the roof and grow large enough to fall on your unit, potentially causing serious damage. Water can also pool behind or beneath the unit and freeze when temperatures drop, creating hidden ice buildup that restricts airflow and drainage. Under normal circumstances, a defrost cycle should take care of the frost or ice. However, sometimes the buildup can be too much for the system to handle and you may need to manually clear off the ice. The defrost action also works in only one direction, which can leave the sides of the heat pump unaffected. How To Quickly Defrost A Heat Pump In Winter Brush off as much snow from the outdoor unit as you can. Switch your system to COOL mode for 15-20 minutes. This will “force” your heat pump to defrost and melt the ice. Wait a few minutes before switching your heat pump back to HEAT mode. Note: DO NOT use sharp objects like a shovel to scrape off the ice, as this could damage the coils, fins, or fan. DO NOT pour hot water directly on the pipes. The sudden temperature change could crack them. How To Keep Your Heat Pump From Freezing During Winter Install a snow hood or cover your heat pump to protect it from heavy snowfall during winter storms. Regularly clear snow and debris from around the unit and make sure any water (whether from rainwater or from the heat pump’s defrost action) drains away from the unit. 3. Why is my heat pump's backup (auxiliary or emergency) heat turning on so often? Your backup heat is designed to take over when the temperature outside drops to between −25°C and −30°C and your heat pump can’t efficiently maintain your home at the desired temperature. It also activates when the heat pump enters defrost mode and may run more frequently during extremely cold weather. Backup heat can also turn on if the thermostat is set significantly higher than the current indoor temperature. How to Minimize Backup Heat Use: Heat pumps work best when left alone to maintain a steady temperature. Set your thermostat to a comfortable temperature once and let it be to reduce backup heat usage, and avoid making frequent or large adjustments. Avoid raising the temperature more than 2°C at a time, and make gradual adjustments if needed. Avoid setting your heat pump to temperatures above 24°C. Turn your backup heating at least 5°C below your heat pump. This is called the set point temperature. 4. What temperature should I set my heat pump to? Heat pumps run best within a specific heat pump temperature range. For maximum comfort and efficiency, it’s recommended to keep your home between 21°C and 23°C. This strikes the perfect balance between maintaining warmth and minimizing energy use. Best Practices: Avoid big, sudden increases (e.g., raising the temperature 4–5°C at once) or high settings (greater than 24°C), which can trigger backup heat and reduce your heat pump’s efficiency. Every degree above 21°C raises your energy costs by about 2–2.5%. Set it and forget it. Constantly adjusting the temperature makes your heat pump less efficient. Set your thermostat to a comfortable temperature and let it be. If you have a ductless system or mini split: Make sure all indoor heads are powered on, set to the same mode, and kept at similar temperatures. Maintaining a steady, moderate temperature helps your heat pump run smoothly, saves energy, and keeps your home consistently comfortable. Heat Pump and HVAC Tips for Winter and FAQs Is it normal for my heat pump to blow cool air in winter? Yes, but only briefly. Your heat pump may blow cool air for 5-15 minutes while it is in defrost mode and it’s working to melt ice on the outdoor unit. This is normal and temporary. If cool air continues outside of defrost mode, check that your system is set to HEAT mode. How can I tell if my heat pump is in defrost mode? When your heat pump is in defrost mode, you’ll notice: Cool air coming from the vents Steam or water coming from the outdoor unit Your backup heat turning on These are all normal signs of a defrost cycle. How long should a defrost cycle last? A typical defrost cycle lasts 5 to 15 minutes. Once it’s complete, your heat pump should return to normal heating automatically. Is ice buildup on my heat pump normal? Light frost on your heat pump is normal, but you should take action if: Ice is thick or covering the sides of the unit Large icicles are forming Airflow appears blocked Excessive ice can reduce efficiency and cause damage if left untreated. Can I remove ice from my heat pump myself? Yes, but you must do so carefully. Do not use sharp tools or hot water. Instead: Brush off loose snow from the system. Switch it to COOL mode for 15-20 minutes. This will “force” the system to defrost. Wait a few minutes before turning the system back to HEAT mode. If you still see excessive ice forming, call a professional to come and inspect your system. Can snow and ice damage my heat pump? Snow can stop your heat pump from working efficiently if the unit is buried in it or exposed to heavy ice buildup. Installing a snow hood, clearing snow regularly, and ensuring proper drainage will help protect your system. Should I set my heat pump to AUTO mode in winter? AUTO mode can cause the system to switch between heating and cooling, which may result in cold air blowing unexpectedly. For the most consistent comfort in winter, always set your heat pump to HEAT mode. Why is my backup (auxiliary or emergency) heat running so much? Backup heat turns on when: Outdoor temperatures are extremely cold (around −25°C to −30°C) The system enters defrost mode The temperature setting on your thermostat is raised too quickly This is normal, but frequent use of backup heat can lead to a spike in your energy bills. How can I reduce my backup heat usage? Increase the temperature no more than 2°C at a time Keep your thermostat below 24°C Set backup heat 5°C lower than your heat pump set point Keep your thermostat set to a steady temperature, and avoid frequent changes What temperature should I set my heat pump to in winter? For best comfort and efficiency, set your thermostat between 21°C and 23°C. Every degree above 21°C can increase energy costs by 2–2.5%. Should I turn down the temperature on warm days? It isn’t advisable to turn your heat pump temperature down or make large adjustments frequently. Instead, maintain a consistent, moderate setting for maximum efficiency. Do ductless (mini-split) systems need special settings in winter? Yes. Make sure: All indoor heads are turned on All units are set to the same mode (HEAT) Temperatures are set similarly across zones or rooms Use these quick, essential tips to prepare your heat pump for the chill ahead. A few minutes now can keep your heat pump running strong through the snow. Have more questions? Visit Our Heat Pump Learning Centre to find everything you need to know about your system, or schedule a service call with us at 1 (800) 458-1289.
