Heating & Cooling

16 Reasons Your Heat Pump Doesn’t Blow Hot Air

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Hubert Miles

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Heat pumps are popular due to their energy efficiency. Heat pumps work by providing cool air in the summer and warm air in the winter. Often times, especially people who are used to gas heat, people feel their heat pump isn’t working. Sometimes this is the case due to a mechanical failure, but it can also be a misdiagnosis.

So, what are the reasons that your heat pump doesn’t blow hot air? These are the most common causes of a heat pump that won’t heat anymore:

  • Dirty filters, coils, and surfaces.
  • Leaks in the ductwork.
  • Malfunctioning thermostat or thermostat settings.
  • Frozen components.
  • Broken compressors, coils, and other parts.
  • No power or not enough in general.
  • It’s running a defroster.
  • It’s cold outside (I’m not being silly. I’ll explain I promise)

Throughout this article, you’ll also learn about the details of every reason, how you can fix your heat pump, and when it’s time to get a new one. You’ll also find out what the signs of a failing unit are and how long they last.

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Why Won’t My Heat Pump Blow Hot Air?

Heat pumps are notorious for having problems when you need them to work during a cold season. There are countless reasons that it might stop working as it should, so let’s review each of them below in detail.

1. The Exterior Condenser is Dirty

After years of use, all exterior condenser coil will eventually accumulate dust and debris restricting airflow. When air is pulled through the vents, it also collects dirt, dust, grass clippings, and other debris that you don’t want there. You can fix this common problem by having your system cleaned and serviced annually.

2. There’s a Blockage Outside

If you have plants around the edges of your heat pump’s vent outside, then you’ll undoubtedly experience troubles. There should be a minimum of 2 feet of clearance around the unit to allow an optimal flow to pull air from outside to warm up the coils and get everything moving smoothly. Trim back any bushes, trees, or other plants that are blocking the vents.

Be sure fencing and other shelters around the heat pump meet clearance requirements.

3. The Filter Might Be Clogged

If you have a clogged air filter, there’s nothing you can do except replace it (or clean it if you have a washable air filter). If your air filter is clogged, it restricts the airflow your heat pump needs to function properly. slowed down dramatically.

Running a heat pump without the air filter is not recommended. However, it may be necessary for a night until you can get to the store to purchase a new one. If you run the unit without the air filter for long periods of time, the evaporator coil can get dirty and stop working.

4. There’s a Low Refrigerant Charge

If you have a low refrigerant charge, then you won’t be able to get any heat transfer from the heat pump. The refrigerant is needed to cool the condenser coil to a point below the outside air to allow heat transfer. It should pull outside air across the condenser coil, transferring heat from the air to the refrigerant as it travels back to the evaporator coil. With a low charge, you’ll be left with little to no heat.

If you have a low refrigerant charge, there is likely a leak somewhere in the system. You’ll have to seek professional help to deal with this common issue since it involves dismantling and repairing the internal components.

For details on how heat pumps work to transfer heat using refrigerant, check out the video below.

5. You Might Have No Power to the Condenser

Although it seems silly, there’s a chance that the circuit break leading to your condensing unit in the heat pump could be tripped. Check your electrical panel and service disconnects to be sure the breakers have not tripped.

If the breakers have not tripped, there could still be a break in the power somewhere. If your condenser is not starting, you could have a blown capacitor.

When dealing with electrical components you should always call a licensed heating and cooling contractor to trace down where the problem is located.

6. It’s an Old Unit

Unfortunately, old heat pumps tend to have one problem after another. As mechanical components age, they break down more frequently. If your heat pump is old, then you’ll probably have to replace it soon.

New federal standards for R-410a refrigerants are making it harder and harder to repair older systems with R-22 refrigerant. Many HVAC contractors will no longer work on R-22 systems and will only install replacement systems.

7. You Could Have a Broken Thermostat

Thermostats are often the reason that heat pumps stop working. If there’s no power, a tripped fuse, fried internals, dead batteries, or even just small malfunctioning parts, your thermostat could prevent the pump from heating your home. The good news is that most thermostats aren’t too expensive. Try out this Heagstat Thermostat to program your heat pump for cheap.

8. Thermostat Might Be on the Wrong Settings

On the other hand, you could’ve accidentally set the thermostat to the wrong settings. Most thermostats these days have options for cooling, heating, and auto which toggles back and forth between heat and cool as needed to maintain the set temperature.

There is also a Fan setting for Auto and On. If your thermostat fan is set to ON your heat pump may not be engaged at the moment. In the ON setting the fan will run continuously regardless of the outside temperature.

9. The Coils Are Iced Over

Frozen coils are caused by the heat pump not being used when it’s too cold outside. If you wait for too long, they could freeze, preventing them from warming up when you start the thermostat. To keep this from happening, turn on your heat pump before it reaches below 32 F (0 C).

If your heat pump coils are icing over, this is usually caused by restricted air flow around the unit or the defrost function is not working properly.

10. The Reversing Valve May Have Failed

Reversing valves in a heat pump system are used to direct the flow of cold and warm air. This process depends on the valves to do their job properly. If the valves in your system are broken, you could be flooding your home with cold air as the system gets “stuck” in one direction. They might be stuck sideways, blocking airflow completely.

11. Air Duct Leaks Are Possible

When the air ducts that transfer air from one place to another have holes or loose connections, then there’s a huge issue. Air that leaks out obviously won’t make it to the places in your home that need warm air. Instead, it’ll leak outside, which doesn’t do anything for you and your family.

This can cause air to leak into the attic, basement, or crawl space depending on where your ducts are located. Air loss like this can cause no heat to reach certain rooms in your home.

You’ll need the help of a professional technician to fix this issue.

12. The Compressor Might Have Failed

The compressor works to remove the cold air from your house while introducing warm air to reverse the natural cooling process of an air conditioner unit. If the compressor is malfunctioning, it won’t be able to heat up your home. Instead, it’ll push out lukewarm air from all the vents.

Compressor repairs can be expensive. Usually this occurs from the compressor running dry with no refrigerant.

13. It’s Just Defrosting

Most heat pumps go through a defrosting period once an hour or so. This process is designed to prevent the coils from freezing, which would render your heat pump useless. During this time, the heat pump will be focusing on heating the coils rather than your home. It’s not broken, it’s just maintaining itself.

14. Your Thermostat is in Auto Recovery Mode

Programmable thermostats will go through an Auto Recovery Mode period between scheduled temperature change settings. For example, my thermostat displays a RECO message between program settings.

During this time, your heat pump tries to change the temperature gradually which could make the air feel cool. This is part of the energy-saving feature built into the thermostat.

15. The Emergency Heat Has Failed

Heat pumps have emergency heat strips that kick in to assist the heat pump when the temperature drops below 30 degrees. If your heat strips have failed, the system may be trying to engage the emergency heat but it’s simply not responding.

16. It’s Cold Outside

Now I know this seems like a really dumb statement. Of course, it’s cold outside you’re running the heat for a reason. Let me explain what I mean.

Heat pumps work by transferring heat from outside air. In the video above, it outlines how the heat pump does this. However if it’s 60 degrees outside it stands to reason that there is more heat to transfer than when it’s 20 degrees outside.

Heat pumps typically operate on about a 20 degree differential. Your body temperature is 98.6 degrees, however if the air coming out of your vents is at 85 degrees it will feel as through your heat pump is not working properly when it actually is.

The video below does a good job of explaining this phenomenon.

Should You Repair or Replace Your Heat Pump?

According to Improve Net, replacing a heat pump can cost up to $5,100. That’s a whole lot of money for anyone, regardless of your income level. Sadly, all heat pumps are limited to only last for so long.

Let’s examine the pros and cons of replacing vs. repairing a heat pump:

Pros of Repairing a Heat Pump

  • You’ll save tons of money this way. Perhaps the biggest draw of replacing an existing heat pump system is that you don’t have to fork out the aforementioned $5.1K. Instead, you’ll only have to spend about $400 to $1,100.
  • Your home will have the same heat pump without you having to worry about introducing something foreign. You don’t have to replace random bits and pieces to make sure that they function together properly.

Cons of Repairing a Heat Pump

  • You’ll inevitably have to repair even more parts. When heat pumps get old, you’ll have to replace one component after another. For more information about how many years you can get out of your heat pump, keep reading.
  • You’ll void the warranty in most cases. Many heat pumps that come with a warranty require professionals to be the only people who work on the unit. If you try to DIY the repair, you could risk getting rid of warranties for the rest of the duration.

Pros of Replacing a Heat Pump

  • Getting a brand-new heat pump means you don’t have to worry about any problems for plenty of years to come. You’ll also be able to relax without having to worry about doing any of the research or work yourself.
  • As mentioned above, most heat pumps include a warranty. By hiring a professional to do the installation, you’ll be able to reap the benefits of a multi-year contract that covers all sorts of manufacturer defects.

Cons of Replacing a Heat Pump

  • Replacing a heat pump is very costly. It’s one of the most expensive repairs of your home’s air circulation system, but it’s essential to have during the cold months of the year.
  • If you experience any issues with a new heat pump, it could be because it’s completely new to your home’s circulation system. You might end up having to replace ducts, vents, and other parts to get it working properly.

How to Fix a Broken Heat Pump

Since there are so many causes of a malfunctioning heat pump, there’s no one way to explain how to fix every issue at once. However, you can follow specific safety guidelines to ensure that you don’t get hurt in the process. If you’re worried about doing it yourself, always hire a professional.

Here’s the five-step process to diagnose and fix a broken heat pump:

  1. Find the source by testing the breakers with a multimeter. These tools allow you to figure out what has electricity and what doesn’t. If everything is powered, you can start by cleaning the filter, vents, and removing anything that might be obstructing the exterior. You may have to hire a pro to diagnose the source.
  2. Turn off the power at the circuit breaker before you work on anything. It’s not worth risking your health to fix a heat pump. Once it’s all off, you can start to examine the unit.
  3. Once you’ve found out what the problem is, see if there’s anything you can do to repair it rather than having to replace it. Every part of a heat pump system costs less than a new pump, so why not save some money? In most cases, all you’ll need is a few hand tools.
  4. Consider hiring someone to fix the issue vs. doing it yourself. Some techs offer warranties on parts, while others don’t. If it’s something as simple as a filter replacement, you can remove the screws and replace the filter or clean it in seconds. Complex procedures that require pro help include air duct leaks, refrigerant issues, and valve problems.
  5. If the coils are frozen, you may be able to save them by warming them up. Typically speaking, the coils are warmed by running the heat pump. You might just have to give it a few hours to kick the frost off. If they’re permanently damaged, then they’ll require replacement.

Always test your work and ensure that everything is secure before you run your heat pump for several hours on end. If you forget to replace the filter or you accidentally leave wires exposed, all sorts of problems can occur.

How to Get the Most Out of Your Heat Pump

Heat pumps are debatably some of the best inventions for cold environments. We all know how useful they can be, but there are several ways that you can extend the life of your heat pump while also getting more usage out of it.

Whether you live on a freezing mountain or a seaside city, you can benefit from this section. Here’s a list of methods that you can try out to get the most out of your heat pump:

  • According to Heat and Cool, you should clean your heat pump filter once every 8 to 12 weeks. If you use it every day during the winter, you might want to consider narrowing it down to 5 to 6 weeks. On the other hand, never let the time between cleanings exceed 15 weeks.
  • Follow the recommended maintenance schedule. Much like an automobile, you can prevent small problems from becoming more severe if you follow the recommendations. These tips might include replacing the coils every so often, checking electrical connections once a season, or getting new valves to keep the air flowing correctly.
  • Have your air conditioner and heat pump units inspected annually. These procedures should be done right before it gets cold outside. Inspections are inexpensive and they provide peace of mind, not to mention the fact that they’ll prevent you from freezing if something needs to be repaired.
  • Remove anything near vents around your home, and don’t forget to clean the dust off regularly. Lamps, fake plants, and entertainment centers can reduce the air circulation in your home. These setups have the ability to drastically cut down on the amount of warmth that you get from your heat pump.
  • Consider getting a fan to blow warm air around the house. Contrary to popular belief, fans, don’t create cold air. They simply move it at a faster rate, pulling stagnant air and making it feel a bit better. By turning on a fan, you can move the warm air from your heat pump to warm up your house quicker.

How Long Do Heat Pumps Last?

Some heat pumps last longer than others. It should come to you as no surprise that people who live in a cold climate will use their heat pump more often than those in a warm area.

For example, you wouldn’t use a heat pump too often in Phoenix, Arizona, but just a hundred or so miles away in Flagstaff, you might freeze if you don’t! The people living in Flagstaff will get a shorter lifespan from their heat pumps since they’re using them much more often.

Glasco Heating & Air states that heat pumps last about 15 years on average. With proper maintenance, you’ll be able to increase that estimate by quite a bit. In fact, it’s not rare to see a house that gets between 20 to 25 years of top-notch usage from their heat pump.

On the other hand, if you always let the coils freeze and you refuse to clean the filter, you’ll end up shaving years off of your heat pump. You’ll have to spend tons of money repairing and replacing them far more often than you should.

In short, heat pumps are designed to last for 15 years, but your maintenance routines (or lack thereof) can and will directly impact the longevity of the unit. Small cleanings and following the recommendations above will be the best course of action.


Heat pumps are used by millions of homeowners and renters around the world every day. They’re sometimes used for comfort, while other people quite literally need them to survive. By following the suggestions throughout this article, you’ll prevent your heat pump from having a shortened life.

Here’s a quick recap of the post:

  • Small repairs including clogged filters, frozen coils, and blocked vents can be the reason that your heat pump isn’t working as it should.
  • If you’re not familiar with electrical work, call a professional to get a quote and possibly a warranty.
  • Replacing a heat pump can cost up to $5,100 while repairing it can cost as little as $400.


Photo of author

Hubert Miles

I've been conducting professional home inspections since 2002. I'm a licensed Home Inspector, Certified Professional Inspector (CPI), Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
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