Troubleshooting Tips for a Heat Pump Not Heating

It’s frustrating when your heat pump is not working the way it’s supposed to. If your heat pump is not heating, the chill in the air isn’t just outside - it’s in your home. Learn why your heat pump is not blowing hot air or why the heat pump is blowing cool air in heat mode. 

Then learn if it’s a problem you can fix yourself or if it’s time to call for HVAC repair.

Keep in mind that heat pumps don’t blow hot air like furnaces. Instead, they blow a steady stream of warm air. This air is usually between 85 and 93 degrees Fahrenheit, but the air feels cool to us because our average body temperature is 98.6 degrees Fahrenheit.

But if your heat pump truly is not heating, there are four main causes. 

The first thing to check is your thermostat and thermostat settings. There are different solutions for different issues.

Issue #1: The thermostat is still set to Cool. What to do: Switch to heat mode.

Issue #2: The heat pump is blowing cool air in heat mode. What to do: Check the thermostat settings and be sure you have the fan set to Auto rather than On. If the fan is set to On, the system will blow air even when the heat pump is not actively heating.

Issue #3: The heat pump is in Defrost mode. Check the thermostat, and if it says the unit is in Defrost mode, it will be blowing cool air. What to do: Wait. Once it exits Defrost mode, it should resume heating as normal.

Issue #4: You have a faulty thermostat. What to do: Try some thermostat troubleshooting tips. If they don’t solve the problem, call for HVAC repair. 

If your heat pump stopped working, it may be suffering from low airflow. Dirty air filters can cause the unit to struggle to heat your home, and even overheat and shut down. Restricted airflow at the outdoor unit can also cause heat pump problems. 

What to do: Check for a clogged air filter. Change it if it’s dirty. Check the outdoor until. Clear away any leaves, debris, or snow from the top. Trim any vegetation that is nearby. If your heat pump is still not heating, call an HVAC professional.

If the unit was working fine a few days ago when you were running it in cooling mode but the heat pump does not heat now that you switched to heating mode, it could be a problem with the heat pump reversing valve. 

This is the vital heat pump component that controls refrigerant flow and reverses direction when you switch the unit from cooling mode to heat mode. It may be stuck or it may have failed. 

What to do: Visit the heat pump reversing valve troubleshooting page for some tips. You may need to call an HVAC professional. 

Another reason your heat pump is not heating could be that it’s low on refrigerant. If it worked hard in extreme heat over the summer or it’s an aging unit, and now it has low airflow,  it may have a refrigerant leak. That’s the only cause of low refrigerant levels.

What to do: If you hear a hissing sound near the outdoor unit, see liquid pooling, or have a frozen evaporator coil, you could have a refrigerant leak. Call for HVAC service right away.

Make it a point to perform regular heat pump maintenance. Just like regular tune-ups, tire rotations, and brake checks on your vehicle can keep it running safely and more efficiently, maintaining your heat pump system can help your heat pump run more efficiently and potentially increase its lifespan. Neglecting maintenance can cause problems and cause your heat pump to fail sooner. 

Your heat pump works hard to keep you comfortable all year long. Regular air filter maintenance can prevent a lot of problems. Change standard HVAC air filters every 1-3 months depending on the quality of the filter. Clean the reusable mini-split filters as recommended. 

Trane heat pumps and mini-splits are premium heating and cooling systems that perform best with regular maintenance. Protect your investment and schedule heat pump service visits for each fall and each spring. Be sure to hire an HVAC company with expertise in heat pumps or ductless mini-split systems.

When you opt into Trane Diagnostics via the Trane Home App, you can give your dealer remote monitoring capabilities of your heat pump system. Your Trane smart thermostat sends data in real-time to your dealer, alerting them to any issues, sometimes before you even realize there’s a problem, and even while you’re on vacation.

They can run heat pump troubleshooting tests to narrow down or even pinpoint the problem. In some cases, they may be able to fix the problem remotely. In this situation, they would ask for one-time dealer remote access (DRA). 

If they need to schedule on-site heat pump repair services, the HVAC technician will arrive at your home with the knowledge gained from remote access. This results in shorter service calls and ensures the technician has the proper replacement parts. 

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Kimberly Sexton, Senior Systems Engineer

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