6 Common Heat Pump Problems and Their Solutions

Tony Carrick
Written by Tony Carrick
Updated April 12, 2023
Girl reads a book while wrapped in a blanket
Photo: Anton / Adobe Stock


  • Heat pumps move heat into or out of the home, depending on whether you’re cooling or heating it. 

  • Look for signs of heat pump problems, like odd smells or sounds, so you can troubleshoot them immediately. 

  • You can troubleshoot some problems by replacing dirty air filters, checking that your registers are open, and cleaning your coils and fans. 

  • Only an HVAC pro can tackle some issues like adding refrigerant or fixing an electrical problem.

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Whether you’re hosting a game night in the winter or a barbecue in the summer, the temperature in your home is essential to everyone’s comfort. But what happens if your heat pump malfunctions? Learn the most common heat pump problems and potential solutions to ensure your home stays comfortable year-round.

What Is a Heat Pump and How Does It Work? 

A heat pump is an electric HVAC system that can provide heat during the winter and cooling during the summer. It works by transferring heat either out of the home or into it depending on whether it is warming or cooling the house. 

During cold weather, the heat pump uses its refrigerant-filled coils to transfer heat from the outdoors to inside the home (yes, warm air is still present outdoors even when the weather is cold). During warmer months, the heat pump uses a reversing valve so the coils can work in the opposite direction to absorb heat from the indoors and pump it outside, cooling the home.

Heat pumps are popular because they’re among the most efficient residential HVAC systems. Since they provide both heating and cooling, you don’t need to install two separate units. Though heat pumps are very reliable, it's always ideal to be ready to troubleshoot any heat pump problems that might arise.

1. Heat Pump Won’t Turn On

When your heat pump doesn’t start at all, one of these common causes may be to blame.

The Thermostat Isn’t Wired Correctly

Check to see if your thermostat is not working properly by checking the display for any error messages, alerts, or other unusual activity. You should also make sure it is displaying the correct setting: it should be set to heat, with the heat pump marked as on. If your thermostat was purchased a long time ago, it’s possible it isn’t a model that can work with heat pumps and might need to be replaced. Finally, if the thermostat was recently replaced, the issue could be with your wiring—talk to a local HVAC repair company to check that everything is hooked up properly.

There’s No Power Source

A heat pump requires a significant amount of power, which can cause your circuit breaker to trip. If you suspect this is the case, reset the circuit breaker to restore power. If it’s icy outside, it’s possible that the blower has frozen and tripped the circuit breaker. 

If the defroster doesn’t run on its own, turn it off so the condenser unit can take over and defrost. If the breaker trips up frequently, there could be a bigger underlying issue an HVAC professional should look at that.

The Starter Capacitor Needs to Be Replaced

You know how older gas ovens emit a clicking sound to indicate that the gas is coming out, even when there’s no flame? If you hear a similar clicking coming from your heat pump, you could have a faulty starter capacitor, the component responsible for sending an electrical charge to the motors. If you suspect this is the issue, hire an HVAC technician near you to replace this part.

Your Registers Are Closed

Your heat pump may be working just fine, but you won't feel it if the registers on your ducts are closed. Since registers are often located out of sight and out of mind in the ceiling or on the floor near the wall, you may not know they’re in the closed position.

Grab a step stool and check to ensure the louvers on the registers are open. Be wary whenever closing your registers. Doing so reduces airflow, straining your heat pump and ultimately shortening its life. 

You Have a Faulty Reversing Valve

Your heat pump's amazing ability to switch from blowing warm air to make your home toasty in the winter to blasting cold air to cool it down in the summer is possible thanks to a little-known part called a reversing valve. When that valve malfunctions, your heat pump may be unable to switch from hot to cold and hence won’t turn on. 

Other symptoms of a faulty valve include reduced heating and cooling performance and high utility bills. If the valve is faulty, you’ll need to call an HVAC technician to replace it.

2. Heat Pump Is Running Constantly 

Several issues might be causing your heat pump to run endlessly. Identifying the problem sooner rather than later is key to preventing an overworked heat pump from breaking down and incurring a higher HVAC maintenance cost.

You’re Asking Too Much of Your Thermostat

Yes, the point of your HVAC system is to cool your home in the hot summers and keep it cozy and warm during those long winter nights. 

However, if you have your settings on the very high or very low end of the temperature spectrum, your heat pump will work overtime to achieve that goal and never shut off. Make sure to figure out the ideal heat pump temperature setting, and don’t deviate too much.

Your Air Filters Are Dirty

Clogged air filters are one of the most common causes (and one of the easiest to remedy) of a constantly running heat pump. If you’ve been procrastinating on changing those air filters every few months, chances are they’re inundated with dust, pollen, pet dander, and other debris they’ve collected.

A clogged filter restricts airflow, forcing your heat pump to work overtime to pull air into the system. Open the returns on your HVAC system, examine the filters, and replace them if they’re full of debris. 

Your AC Coils Are Dirty 

Your heat pump has two coils that create warm and cool air: an evaporator coil and a condenser coil. Over time, dirt and debris can build up on these coils, causing them to become less efficient. When this happens, your heat pump must work harder and run longer to cool and heat your home. Whether you clean those dirty coils yourself or hire an HVAC pro to do it for you, it’s best to do so once a year to keep your heat pump in working order. 

Refrigerant Is Leaking 

Leaking refrigerant is one of the most common causes of heat pump problems. Your heat pump uses this liquid chemical to cool and heat air. As your heat pump’s refrigerant supply slowly dwindles, it will struggle to meet the setting on your thermostat, causing it to run longer. 

Other signs of leaking refrigerant include ice buildup on the evaporator coils, increased indoor humidity, and rising utility bills. If you think your heat pump is leaking, call a professional HVAC repair company to locate the leak and make the repair. 

The Compressor Needs Replacing 

This component controls how much power is delivered to your heat pump; when it’s broken, your heat pump may never shut off. Call a local HVAC professional to have the part looked at and possibly replaced.

3. Heat Pump Won’t Cool

If your heat pump won’t cool your home, it may need a simple cleaning or may require new parts. Here’s how to diagnose the potential causes for your heat pump not working.

The Thermostat Isn’t Communicating Properly

Sensing a pattern? Check the thermostat’s settings and make sure it is set to cool with the temperature you want. If it is displaying the correct settings, it might not be communicating with the heat pump or is misreading the temperature in your home. A local heat pump or HVAC technician should be able to troubleshoot further.

The Reversing Valve Is Broken

The reversing valve is the component that either moves hot air from your home outside (when your heat pump is in cooling mode), or brings hot air inside (when in heating mode). If your heat pump is on and set to cool, but is blowing warm air, the reversing valve may need to be replaced.

It Needs a Cleaning

Over time, the coils and the fan in your heat pump can get dirty, preventing it from emanating heat. You should be cleaning your coils, filters, and fans regularly (monthly for the filters, every eight to 12 weeks for the coils and fan). Regular maintenance for your heat pump should be scheduled at least once per year.

The Refrigerant Is Low

If the refrigerant levels are low or if there is a leak, the heat pump won’t be able to cool (or heat) your home properly. Leaks usually occur at connector points, and the best way to prevent them is by scheduling regular maintenance for your heat pump.

4. Heat Pump Is Blowing Cold Air or Won’t Heat

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Photo: New Africa / Adobe Stock

It may sound obvious, but start with the thermostat—is it set to cold or hot? If the settings are where you want them and your heat pump is still not heating, investigate these other potential causes.

The Fan Is On

Check your fan control settings. If you run your fan continuously, your system may not be actively heating; reset the settings to heat mode, and the fan to auto mode, to get things back on track.

There’s a Blockage

Your heat pump pulls hot air from outside and redirects it into your home. If the vent outside is blocked—either by leaves, snow, ice, or other debris—your heat pump will struggle to work efficiently or at all. Check the exterior of your home and clean up anything that might be getting in the way.

The Air Filter Is Dirty

An excess of grime built-up on the filter can impede airflow to the compressor, which is responsible for heating the air. Check your filter every month and change it when necessary.

Refrigerant Is Low or Leaking 

While it may sound odd, your heat pump needs refrigerant to create heat. When that refrigerant is low, your heat pump will blow cold air. The culprit could be a leak in the system due to a faulty TXV HVAC valve. Call an HVAC professional to determine if there’s a leak and to refresh the heat pump’s refrigerant. 

The Air Ducts Are Leaking 

While most people focus on the heat pump when their HVAC system isn’t cooling or heating their home properly, the problem may be a leak somewhere else. If you’re noticing increased dust in the house, hot and cold spots, and higher energy bills, you may be dealing with leaky air ducts. If you believe this is the issue, contact an HVAC professional to help locate and repair the leak.

5. Heat Pump Is Making Odd Sounds

Heat pumps are powerful machines, so expect them to make a fair amount of noise (and usually more noise than a furnace would), but if your unit is making any of the sounds listed below, take a closer look.

Rattling Noises

Rattling sounds often indicate that a part or several parts are loose. Check every component and tighten any parts that seem to be loose, like the cover panel.

A Loud Banging

A loud banging suggests that a part, a piece of ice, or other object has found its way inside and is repeatedly being hit by the fan’s blades. Turn your heat pump off and see if you can find the source and remove it.


If there is heavy rattling after you’ve tightened all the screws or a sound of vibration, get a professional to inspect the unit to rule out any coolant piping or air handler problems.

Grinding, Buzzing, or Gurgling

These sounds indicate you should get your device looked at right away. A grinding sound suggests the motor bearings are dirty, while a buzzing might mean the coils are malfunctioning. If you hear something like gurgling, you likely need to recharge your coolant.

Incorrect Heat Pump Size for Your Home 

Bigger definitely isn’t always better when it comes to heat pumps. If you get the wrong heat pump size for your home, it could begin making odd noises. A heat pump that’s too large for the house will heat or cool the home too quickly, preventing it from completing a cooling or heating cycle. This rapid cycling will wear out the heat pump’s motor, shortening its life. 

6. Heat Pump Smells Weird 

You can often detect what’s ailing your heat pump by following your nose. Dirty sock odors, burning smells, and fishy aromas are clear signs of problems with your heat pump system. 

There Is Mold Growth

If your heat pump smells musty, chances are there is mold growing on its evaporator coils or in the ductwork. HVAC pros refer to this issue as “dirty sock syndrome.” You’ll need to call a professional to clean the heat pump’s coils and your ductwork if your heat pump suffers from this problem. 

Don’t delay; despite its funny name, mold growing in your HVAC system is no laughing matter. This issue can cause serious health problems, including headaches, eye and skin irritation, and even difficulty breathing. 

You Could Have Pests

One of the more unsettling causes of a foul smell emanating from your heat pump system could be pests. Roaches, rodents, and other creatures can find their way into your vents and other parts of your HVAC system through cracks and gaps and then expire. The smell of these pests will then emanate throughout your home as your heat pump blows air through the ductwork. If funky smells are coming from your ductwork, hire a professional to inspect and clear out any pests. 

Electrical Issues 

Odd smells are often the first sign of electrical problems in your heat pump system. If yours has a burning odor, it’s likely the result of faulty wiring in your system. You may also detect a fishy smell, which indicates various electrical problems, including an overheated motor or wiring issues. If you detect either, shut off your system and call a professional right away. Electrical issues in your heat pump can create a dangerous fire hazard. 

C.E. Larusso contributed to this piece.

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