A central or wall-mounted heat pump that stops producing heat can become a serious source of frustration—especially during Québec’s harsh winters. While this type of system is known for its efficiency, several factors can affect its proper operation. This article helps you understand possible causes, steps to diagnose the issue, and solutions to resolve it quickly.
Understanding How Your Heat Pump Works
Key components to know
A heat pump generally consists of three main elements: the indoor unit (usually wall-mounted or ducted), the outdoor unit (housing the compressor), and the thermostat that regulates the system. These components must work in sync to capture, transfer, and distribute heat throughout the home. If one part fails, the entire system is affected.
Heating mode operation
In winter, the heat pump extracts heat from the outdoor air—even in cold temperatures—and transfers it indoors. This process is made possible by a refrigerant and a compressor that circulates it. When the system no longer heats, it usually means there’s an imbalance in this thermal cycle: either heat isn’t being captured properly or it isn’t being transferred or distributed effectively.
Common Reasons a Heat Pump Stops Heating
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Incorrect or faulty thermostat settings
A poorly programmed or defective thermostat can prevent the heat pump from entering heating mode. Even if the indoor temperature seems reasonable, the system might not detect the need for heat if the sensor is faulty or the settings are wrong. Ensure the thermostat is in “heating” mode and that the target temperature is higher than the current room temperature.
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Clogged filters
Dirty filters block airflow, which limits the system’s ability to heat your home efficiently. This restriction may also cause the unit to overheat or trigger a safety shutdown. Cleaning or replacing filters every three months (or more frequently depending on your environment) is a simple but essential step.
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Low refrigerant level
A lack of refrigerant reduces the system’s heat transfer capacity. This may be due to a leak or poor maintenance. Only a certified technician can resolve this by checking pressure levels and refilling the refrigerant if necessary.
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Frost on the outdoor unit
Light frost is normal in winter, but heavy ice buildup blocks heat exchange. Efficient heat pumps have an automatic defrost mode. If this mode fails or doesn’t activate, the outdoor unit may freeze up completely, preventing it from heating your home.
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Electrical issues
A tripped breaker, blown fuse, or poor connection can cut power to the heat pump. This issue might go unnoticed if the fan still runs without producing heat. Check your electrical panel and connections to rule out this cause.
Self-Diagnosis Steps
Before calling a professional, it’s worth checking a few basics:
- Confirm heating mode: Ensure the thermostat is set to “heat” and not “cool” or “auto.”
- Adjust the target temperature: Make sure the set temperature is higher than the room’s.
- Clean the filters: If you haven’t done this recently, a simple cleaning may solve the issue.
- Inspect the outdoor unit: Look for excessive ice or a blocked fan.
- Check the electrical panel: A tripped breaker may be the direct cause.
These simple actions can sometimes restore proper function without costly repairs.
Warning Signs Not to Ignore
Unusual noises
Clicking, grinding, or vibrating sounds may signal a fan issue, compressor problem, or misaligned mechanical part. These sounds shouldn’t be ignored, as they often indicate a more serious failure.
Heavy frost buildup
If your heat pump is covered in thick frost or ice, the automatic defrost cycle is likely malfunctioning. This significantly reduces efficiency and may damage components. Stop using the system and call a technician.
System won’t turn on at all
If the unit doesn’t respond—even after adjusting settings or resetting the breaker—it may indicate a deeper electrical issue or faulty component (circuit board, relay, defective thermostat, etc.).
Preventing Problems and Improving Energy Efficiency
Maintain to heat better
An annual inspection is recommended to prevent breakdowns and maintain peak performance. It should include:
- Full cleaning of filters and coils
- Refrigerant level check
- Defrost system inspection
- Electrical connection check
A well-maintained heat pump consumes less energy and delivers consistent comfort, even in deep winter.
The importance of automatic defrost
The defrost mode prevents frost buildup on the outdoor unit. It activates in cycles when the system detects reduced efficiency. If it malfunctions, heating performance drops quickly. A technician can test and repair the defrost function if needed.
Improve your home’s insulation
Even with a high-efficiency heat pump, warm air can escape through cracks or poor insulation. Improving insulation around doors, windows, walls, and attic can help maximize performance.
When to Call a Professional
Contact a qualified technician if:
- The issue persists after your checks
- You hear abnormal noises
- The outdoor unit remains frosted
- The system won’t start or only blows cold air
- The thermostat stops responding
A professional can diagnose the issue accurately, replace faulty parts, and advise on future maintenance.
Conclusion: Act Quickly to Restore Optimal Comfort
A heat pump that no longer heats could be caused by something as simple as an incorrect setting or as complex as a mechanical fault. By understanding potential causes, you can act quickly and avoid further damage. If basic checks don’t fix the problem, professional intervention is essential.
By maintaining your heat pump regularly, keeping the filters clean, and watching for warning signs, you’ll boost both efficiency and lifespan. Proper care means reliable comfort—year-round.
