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How to troubleshoot a wall-mounted heat pump that is not heating properly?

The Expert's Guide to Troubleshooting a Wall-Mounted Heat Pump That Isn't Heating Properly

At AirGreen, a premier HVAC company based in Montreal, we're committed to providing top-notch heating and cooling solutions like wall-mounted heat pumps, also known as mini-splits. In this comprehensive guide, we'll discuss how to troubleshoot a wall-mounted heat pump that isn't heating correctly—an essential skill for homeowners and property managers alike.

The Intricacies of Wall-Mounted Heat Pumps

Wall-mounted heat pumps are an excellent choice for modern, efficient, and flexible heating and cooling. These devices, also referred to as mini-splits, feature an indoor unit that is mounted on a wall and an outdoor compressor, connected via a conduit containing power and refrigerant lines. However, like any machine, they can encounter operational issues from time to time.

Understanding Heating Problems in Wall-Mounted Heat Pumps

If your wall-mounted heat pump is not heating your space as it should, several reasons could be behind this. Among these are issues with the air filters, the thermostat, the outdoor unit, and the heat pump's defrost cycle. To resolve these problems, understanding them is the first step.

Air Filters

Clogged or dirty air filters are one of the most common reasons for reduced heating efficiency in heat pumps. When the filters are blocked, the airflow is impeded, making it hard for the heat pump to warm your space.


Sometimes, the issue might be as simple as incorrect thermostat settings. If the thermostat is not set to the correct mode or temperature, it might result in inadequate heating.

Outdoor Unit

The outdoor unit of your heat pump could also be a culprit. If it's blocked by snow, ice, or debris, it can limit the system's ability to absorb heat from the outdoor air.

Defrost Cycle

Heat pumps operate by extracting heat from the outdoor air. In extremely cold conditions, the outdoor coil may freeze, and the heat pump will enter a defrost cycle to thaw it. During this cycle, the heat pump may temporarily cease to provide heat.

Troubleshooting Steps for a Malfunctioning Wall-Mounted Heat Pump

Check the Air Filters

Inspect the air filters in your heat pump. If they're dirty or clogged, clean or replace them. This simple step can often restore your heat pump's heating ability. As a general rule, filters should be checked at least once a month during peak usage periods.

Inspect the Thermostat

Check the thermostat settings to ensure it's set to heat mode and the desired temperature. If your heat pump has a programmable thermostat, confirm that the schedules are set correctly.

Clear the Outdoor Unit

Ensure the outdoor unit is clear of any debris, snow, or ice. A blocked outdoor unit can inhibit the heat transfer process, reducing the heat pump's ability to warm your home.

Wait Out the Defrost Cycle

If it's freezing outside and your heat pump isn't providing heat, it may be in a defrost cycle. Wait for about 15-20 minutes to see if the heating resumes. If it doesn't, it may be time to call in a professional.

Professional Help

If you've checked all these and your heat pump is still not heating correctly, it's time to call a professional HVAC service provider like AirGreen. There could be more complex issues at play, such as refrigerant leaks or compressor problems, which require expert attention.

A Word on Regular Maintenance

Regular maintenance can prevent many heating problems with wall-mounted heat pumps. AirGreen offers comprehensive maintenance services, which include cleaning filters, checking the refrigerant level, inspecting electrical connections, and more, ensuring that your heat pump operates at its best year-round.