4 Common Heat Pump Problems and Solutions

C.E. Larusso
Written by C.E. Larusso
Updated October 21, 2021
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That rattling sound is trying to tell you something about your heat pump

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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.

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 your thermostat’s 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 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 that should be looked at by an HVAC professional.

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 a technician to replace this part.

2. 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:

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.

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

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It may sound obvious, but start with the thermostat—is it set to cold or hot? If the settings are where you want them, 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.

It Won’t Stop Running

A heat pump that runs constantly can dramatically increase your energy bills and defeat the purpose of having a usually-very-efficient heat pump in the first place.

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.

The Compressor Needs to Be Replaced

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.

4. 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.

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