11 Top Heat Pump Problems and How to Fix Them

When it rains, it pours, right? And when you need it most as you’re shivering in those cold winter days, your heat pump suddenly fails you also! Well, grab an extra sweater and follow these heat pump troubleshooting tips to get it up and working again.

So what are the typical problems for a heat pump? Whether it’s an issue with the temperature settings, malfunctioning parts, or just a weird smell, continue reading to find out how you can address a heat pump failure.

A heat pump operates by using a refrigerant cycle to extract heat from a cooler source (like outside air) and transfer it to a warmer area (like the inside of a building), essentially “moving” heat from one place to another using a compressor and a series of heat exchangers, rather than generating new heat. This process can be reversed to cool a space by transferring heat from inside to outside, making it function as both a heater and a cooler depending on the need. Heat pumps are composed of various parts. These include:

• Evaporator: where the refrigerant absorbs heat (from the air or ground depending on the type) and vaporizers it into a low-pressure gas
• Compressor: increases the pressure to raise the vapor’s temperature
• Condenser: the high-pressure, hot vapor moves to the condenser where it releases heat as it condenses back into a liquid
• Expansion valve: before returning to the evaporator, the refrigerant passes through an expansion valve which reduces its pressure, allowing it to absorb heat again in the next cycle

Two types of heat pumps:

As mentioned above, the evaporator absorbs the heat from two different sources, depending on the type of heat pump. An air-source heat pump extracts heat from the surrounding air, while a ground-source heat pump draws heat from the ground below. This makes the ground-source pump generally more efficient, but also significantly more expensive to install due to the required ground loop installation. Essentially, air-source is cheaper upfront but may cost more to run in colder climates, while ground-source has higher initial costs but generally offers better long-term energy efficiency. The ground-source heat pump will also require a larger area to install the pieces.

Oftentimes, heating pumps seem to malfunction at the times we need them the most. This can be very frustrating! But don’t worry, read through these eleven common heat pump problems and follow the tips to get your heating unit back up and running.

Some of the issues stem from common root causes, so a fix in one area can solve several problems at once. Try the following heat pump diagnostics and get back to enjoying a cozy home.

1. Heat Pump Running Constantly

A heat pump that is running constantly usually indicates a problem with airflow. This is often caused by a clogged air filter, blocked outdoor unit, or issues with ductwork, forcing the system to operate longer to reach the desired temperature. Try changing out the dirty air filter and remove debris that is impeding the airflow (such as leaves, snow, etc.) which makes the pump work harder.

Other potential causes include thermostat malfunction, low refrigerant levels, or electrical problems, so check these components first before calling a technician. In the case of a refrigerant leak, you will need to call a professional service to recharge the system.

2. Heat Pump Is Not Running

Maybe you’re asking, “Is my heat pump broken?” If you’re having the reverse heat pump issue and it’s not running at all, then it could still be solved through addressing some of the same issues. The air duct could be completely blocked and needs to be cleaned or changed to ensure that the air is moving through well. Check the thermostat settings and make sure that they’re on the right function, and not set too high or too low. Remove any debris that may be blocking the outdoor unit.

Another common problem with the heat pump system is simply a tripped circuit breaker. Try the age-old “turn it off and on again” to see if that gets your heat pump up and running again. If the reversing valve is broken, which you might suspect if the pump works in heat mode but not cooling mode, it is best to call for professional help as you can inadvertently damage the valve, causing the refrigerant to leak.

3. Outdoor Unit Is Frozen

If your heat pump’s outdoor unit is frozen, check for a clogged air filter, clear debris around the unit, look for excessive ice buildup on the coil and fan blades (possibly due to blocked condensate drain lines that cause water to freeze there), ensure proper airflow, inspect for a faulty defrost cycle, and consider if there might be a low refrigerant level.

Faulty sensors may not trigger the defrost cycle appropriately, so verify that the sensors are functioning properly.

4. Indoor Air Handler Not Working

First, check the electrical power source for tripped breakers and reset as needed. As always, check for a clogged air filter, and also look for any visible damage in the ductwork. For further troubleshooting of your heat pump issues, check if the condensation pan is full and the drain line is clear, especially if you notice any water leaks. Listen for unusual noise from the fan motor. If it isn’t spinning at all, it may be time to replace it. Lastly, inspect the control board for any visible damage or loose connections.

5. Heat Pump Not Heating

Is your heat pump not heating? First, check if your thermostat is set to “heat” mode and the temperature is set correctly. If so, then inspect the air filter for dirt, as a clogged filter can significantly impede airflow and reduce heating output. Additionally, check for power issues like tripped circuit breakers, and examine the outdoor unit for frozen coils which can block heat transfer. If the problem persists, consider potential issues like low refrigerant levels, faulty thermostat, or a malfunctioning compressor.

6. Heat Pump Not Cooling

On the flip side, if your heat pump isn’t cooling, first check if your thermostat is set to “cool” and at a temperature lower than the current room temperature. Then inspect the air filter for dirt and the outdoor unit for debris. Consider potential issues like low refrigerant levels, which may require a professional contractor to diagnose and recharge, or a faulty compressor if the system cycles on and off frequently.

7. Heat Pump Doesn’t Switch from Heat to Cool or Vice Versa

If your heat pump isn’t switching from heating to cooling or the other way around, the most likely culprits are a dirty air filter, a faulty thermostat, a malfunctioning reversing valve, low refrigerant levels, or issues with the wiring connecting the thermostat to the unit. In the case of a faulty reversing valve, call a professional to avoid causing further damage and leaking refrigerant.

Loose or damaged wires connecting the thermostat to the heat pump can cause incorrect signals, preventing mode switching. Dirty evaporator coils indoors or condenser coils outdoors can affect heating/ cooling performance and switching between the two. A failing starting capacitor can prevent the compressor from starting properly, leading to inconsistent cooling and heating.

8. Heat Pump Is Short-Cycling

If your heat pump is short-cycling (turning on and off frequently), check for issues like: a clogged air filter, dirty coils on the outdoor unit, blocked vents, a faulty thermostat, incorrect unit sizing, poor insulation, a failing starting capacitor, and ensure that there is proper ventilation around the unit.

9. Unit Is Leaking Liquid

In the case of the heat pump unit leaking liquid, the most likely reason is a clogged condensate drain line, which is where condensation from the unit is supposed to drain. Check for debris buildup in the drain line and clean it out if necessary. Other potential causes include a dirty air filter restricting airflow, a broken condensate pan, damaged evaporator coils, or improper installation of the unit. If the leak is significant or you can’t identify the source, contact a professional HVAC technician.

10. Weird Smells

Is your heat pump emitting strange smells? The most likely culprits are a clogged air filter (a potential culprit for nearly every issue), excessive moisture build-up leading to mold growth on the evaporator coils, or a dirty condensate drain – all of which can produce musty or stale odors. Check your filter regularly, clean the coils and drain line, and consider adding a dehumidifier if humidity is high. For burning smells, inspect for dust accumulation on the heating elements and contact an HVAC technician if the issue persists.

11. Heat Pump Blowing Cold Air in Heat Mode

For troubleshooting heat pump problems of blowing cold air, take a look at these possible reasons. Blowing cold air in heat mode is likely caused by a dirty air filter, incorrect thermostat settings (check if it’s set to “heat” and not “cool”), a faulty reversing valve, low refrigerant levels, a clogged outdoor unit, or potential issues with the defrost cycle, which might be preventing proper heating. If your unit is in poor condition, experiencing many of these problems, and older than 10 years, it may be time to look at a heat pump replacement.