Why Is My Heat Pump Blowing Hot Air In Cool Mode?

image of a homeowner feeling hot and sticky due to heat pump blowing hot air in cooling mode

Heat pumps are incredibly versatile HVAC systems that can help regulate the temperature in your home all year round. These units can either provide heating during the winter or cooling in the summer. All you have to do is set your preferred settings. Moreover, it’s easy to switch modes and adjust the temperature to your liking.

However, sometimes you may run into an issue, such as the heat pump blowing hot air in cool mode. What could be causing this? Let’s find out.

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Reasons Why Your Heat Pump Blows Air in Cool Mode

Even though heat pumps are built to last, they’re not indestructible. If a heat pump malfunctions, it’s common for it to blow warm air instead of cool air during the cooling cycle. Therefore, you should be aware of the common culprits behind this issue.

By understanding the reasons why their heat pump might be acting up, you can reduce the chances of it happening again in the future. You can also perform some basic troubleshooting steps before seeking expert help for more complex solutions.

Here are seven things you can check if you’re experiencing this problem:

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1. Malfunctioning Heat Pump Reversing Valve

heat pump refrigeration cycle

The heat pump’s reversing valve is a vital component that enables it to both collect heat indoors and carry it outdoors. In simple terms, this part is responsible for gathering heat outdoors and pushing it indoors.

To achieve these functions, the valve directs the flow of refrigerant. However, a broken reversing valve can cause the heat pump to malfunction and fail to perform as intended.
To fix this issue, you may have to replace the valve and then add refrigerant to the system. This is a complicated process that requires the expertise of trained HVAC technicians.

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2. Heat Pump Thermostat Issues


In some cases, a heat pump’s fan may be blowing warm air around the house because the thermostat was not programmed correctly. You may need to adjust the settings to ensure that the unit is in cool mode. This can be easily done by checking the thermostat settings. In addition, a low battery may also cause the thermostat to malfunction. Therefore, inserting fresh batteries could help. It’s also possible that a tripped breaker could be causing the issue.

If none of these solutions work, the thermostat could be defective and would have to be replaced. Old manual thermostats may also need to be replaced anyway, so this could be a good opportunity to do so. Basic programmable thermostat models are available at a cheap price. On the other hand, more advanced thermostat models with additional features may be more expensive.

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3. Heat Pump Refrigerant Loss

Heat pumps use refrigerant to release heat in different places. The systems are unlike furnaces, which generate their own heat. If there is not enough refrigerant flowing across the system, it will not work efficiently. Even if the thermostat settings are correct and the reversing valve is working, the unit may still blow hot air in cool mode due to a refrigerant leak. In such a case, call a licensed technician to fix the leak and add refrigerant to the system as soon as possible.

4. Clogged Air Filter on Heat Pump

home air filter replacement new and old hvac filter next to each other

The air filters on heat pumps catch dirt and dust particles while allowing air to pass through. However, a buildup of dirt on the filter surface can block airflow, making it difficult for the heat pump to operate. The best solution for this problem is to clean the air filter and remove the blockage. Alternatively, replacing the air filter with a new one is a better option for a fresh start.

Check the manufacturer’s manual for guidance on how often the filter needs cleaning or replacement. Also, keep in mind that environmental conditions around the home can impact the frequency of filter changes. It may be necessary to change the filter more frequently to ensure that the heat pump functions optimally.

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5. Heat Pump Duct Leak

Over time, air ducts can begin to degrade and leak air, causing problems with the distribution of conditioned air throughout the home. Some rooms may feel colder or warmer than others due to inefficient air distribution. It can be challenging to locate the leaks in the ductwork. This being the case, it’s prudent to call in HVAC professionals for assistance. Getting rid of ductwork leaks by repairing the ductwork will not only improve air distribution but also reduce energy consumption and lower monthly bills. Addressing this issue promptly is important for long-term savings and home comfort.

6. Dirty Heat Pump Coil

image of a dirty heat pump coil

The outdoor unit of the heat pump is prone to collecting dirt and debris, such as pet hair, grass clippings, and dried leaves. Over time, the accumulation of dirt can limit the ability of the heat pump coils to absorb or expel heat. Cleaning the outdoor coils regularly with a water hose at low to medium pressure can remove loose dirt. However, be careful not to use high water pressure as it can damage the unit. For stubborn spots, use a light brush to scrub them off.

Indoor coils also require cleaning, but they may be harder to access. Consider hiring an HVAC technician for a heat pump tune-up service to clean the coils thoroughly. While this service is affordable, the results are excellent. Regular cleaning of both the outdoor and indoor coils can help maintain the efficiency of the heat pump and extend its lifespan.

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7. Heat Pump Malfunction Caused by Frosted Indoor Coil

frozen heat pump

The seventh issue that can cause a heat pump to malfunction is a frosted indoor coil. It may not seem correct to say that a frosted coil causes warm air in cool mode. However, when you know how a heat pump operates, it makes sense. When moisture from the air condenses around the indoor coils due to low temperatures, it can cause freezing. This ice can prevent the coil from collecting heat, leading the heat pump to stop working as intended. To fix this issue, shut down the heat pump for a while and put in fan mode. The fan mode will push warm air through the coils, helping to speed up the defrosting process.


Determining Whether to Repair or Replace Your Heat Pump

If you are experiencing issues with your heat pump, you may be wondering whether it is time to replace it. Before deciding, consider a few factors.

  • Heat Pump Warranty: First, check if your heat pump is still under warranty. If it is, then you can take advantage of free parts replacement and labor fees. In this case, it might be wise to keep the heat pump for the remainder of the warranty period.
  • Heat Pump Age: Heat pumps can last for more than a decade. However, as they age, they are more likely to experience wear and tear, which may lead to more frequent HVAC repairs. If you want a reliable system, it may be best to replace an old heat pump that has passed its prime.
  • Heat Pump Repair Vs. Replacement Cost: When deciding, consider the cost of repairs versus the cost of a replacement. Tally up your repair bills for the past few years and estimate future expenses. You may find that getting a new heat pump is more cost-effective than continuing to repair your old one.



Using heat pumps is a great way to keep your home comfortable throughout the year. If you notice your heat pump blowing hot air in cool mode, it may be due to one of the issues described above. Some issues are easy to fix, while others may require a professional technician. In any case, make sure you follow the troubleshooting suggestions above before calling a technician. By considering the factors mentioned, you can determine whether repairing or replacing your heat pump is the best course of action.

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Call Hart Home Comfort For Superior HVAC Services


Looking for top-notch heating and cooling services throughout Nassau County, Suffolk County, and Queens, New York? Look no further than Hart Home Comfort! Our team of certified technicians is here to provide you with all of your HVAC requirements, whether it’s tune-ups, repairs, installations, or replacements.

Our techs are knowledgeable and experienced, ensuring your HVAC system is serviced correctly. Moreover, at Hart Home Comfort, we pride ourselves on offering the most competitive heating and cooling service costs in the area. By using our maintenance services, you can improve your comfort, increase your energy efficiency, and reduce your home heating and cooling costs.
If you need an HVAC repair or replacement, our team can recommend the best system for your home based on your budget and requirements.

We are proud of the services we offer and stand behind all of our work with a guarantee. Therefore, you can rest assured that you’ll be satisfied with our services. Don’t hesitate to schedule a service appointment with Hart Home Comfort today! We even offer free, in-home estimates. Just let our team inspect your unit and provide our expert advice on the way forward. Give us a call, and let us help you with all of your HVAC needs. Click the link to view our service area.

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