Here’s What to Check Before Calling for Help
If your heat pump isn’t working and your house is quickly getting too cold (or too hot), don’t panic. There may be a simple solution.
A heat pump that suddenly refuses to start up can be alarming, especially if you rely on it year-round for both heating and cooling. There are a variety of reasons this can happen that range from simple at-home fixes to more complicated issues that require the attention of a professional.
Understanding Heat Pump Basics
A heat pump is a type of HVAC system that works by transferring heat rather than generating it. During the winter, a heat pump pulls heat from outside air and brings it indoors. In the summer, it reverses the process, removing heat from inside your home and releasing it out.
There are different types of heat pumps, including:
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- Air-source heat pumps (the most common for homes)
- Ground-source (geothermal) systems
- Ductless mini-split heat pumps
Regardless of type, if your heat pump won’t turn on, it’s usually due to one of several common issues.
Common Reasons Why Your Heat Pump Won’t Turn On
Here are the most likely culprits when your heat pump won’t kick on:
Thermostat Settings or Calibration
Sometimes the thermostat can be the culprit. If it isn’t set correctly, your heat pump may be getting the wrong signals to meet your heating or cooling needs. If the batteries are dead, the thermostat can’t communicate with your system and your heat pump won’t know when to turn on.
Tripped Circuit Breaker or Blown Fuse
If there’s been a power surge or the system overheated, a breaker may have tripped. This cuts off power to the heat pump entirely.
Outdoor Unit Obstructions
Debris like leaves, ice, or snow can block your outdoor unit’s air flow, especially during winter, preventing the system from running properly.
Compressor or Capacitor Issues
The compressor is the heart of your heat pump, and it needs a capacitor to get started. If either of these components fails, the system won’t turn on.
Dirty Air Filter
Restricted airflow can cause the system to shut down or freeze up as a protective measure. A dirty filter is a common and often overlooked cause.
How to Troubleshoot Your Heat Pump
Before making a service call, here are a few things you can check on your own:
Check the Thermostat
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- Make sure it's set to heat or cool depending on the season.
- Check that the temperature setting is above (for heat) or below (for cool) the current room temperature.
- Replace the batteries if your thermostat is battery-powered.
Inspect the Circuit Breaker
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- Go to your electrical panel and check for any tripped breakers labeled “HVAC” or “heat pump.”
- Flip the breaker off and back on to reset it.
Examine the Air Filter
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- A clogged filter restricts airflow and can trigger system safety switches.
- Replace the filter if it looks dirty or hasn’t been changed in the last 1–3 months.
Check the Outdoor Unit
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- Look for ice buildup, leaves, or debris around the unit.
- Gently clear any obstructions. If ice is present, turn the system off and let it thaw.
Listen and Observe
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- Is the fan running but there’s no heat or cool air?
- Do you hear clicking or buzzing but nothing happens?
- Strange sounds or complete silence could both be signs of mechanical or electrical problems.
When to Call a Professional for Heat Pump Issues
If your heat pump still won’t turn on after basic troubleshooting, or you notice any of the following signs, it’s time to call an HVAC technician:
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- Unusual noises, such as loud buzzing, clicking, or humming
- Burning or electrical smells coming from the unit
- Frozen or iced-over coils that don’t thaw
- Compressor not starting, even though the fan is running
- Repeated tripped breakers even after reset
It’s important that you engage a professional if troubleshooting was unsuccessful. Licensed technicians have the tools to safely test electrical connections, check refrigerant levels, inspect capacitors and motors, and ensure all system components are operating correctly. Attempting to perform repairs yourself can be dangerous, void your warranty and lead to higher repair costs.
Preventative Maintenance Tips for Your Heat Pump
Keeping your heat pump in good shape can help you avoid unexpected issues. Here are a few simple tips:
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- Change air filters regularly – every 1–3 months, depending on use and manufacturer directions
- Clear the area around the outdoor unit to prevent airflow restrictions
- Keep vents and registers open and unobstructed
- Schedule seasonal maintenance checks with a Lennox-certified technician – typically once in the spring and once in the fall
Seasonal tune-ups and inspections help catch small problems early, ensuring your system is running efficiently and helping to avoid more costly repairs down the road.
A heat pump that won’t turn on can throw your whole day off, especially during extreme temperatures. Fortunately, many of the issues that can cause this can be easily resolved at home. But if your heat pump still isn’t cooperating, don’t wait. Contact your local Lennox dealer to assess and fix the problem.
