Why Does My Heat Pump Not Defrost?

Your heat pump is the only appliance in your house you can rely on to keep you comfortable all year long. Sometimes, heat pumps regardless of being new or old tend to run into problems. For instance, your heat pump might fail to defrost. It is one of the most common issues amongst heat pumps and prompt you to a contact heat pump repair expert. However, there is no need to panic. Here are a few tips that will help you get your heat pump running back to normal.

Poor Airflow

Poor airflow plays a significant role in causing the heat pump to freeze up. This factor is mostly ignored as most homeowners are not even aware of the fact that airflow directly impacts the performance of the coils and the heat pump unit itself. The coils inside a heat pump require a certain amount of airflow to keep them running effortlessly.

However, if the airflow is poor, it will affect the amount of warm air flowing over the coils. Eventually, the heat pumps freeze up as well. If it has been snowing regularly, it might be that the coils are covered with layers of snow and the unit is struggling to defrost it.

In that case, you can manually try thawing out the ice using a special tool. Make sure that you do not hit the unit with a hard object in an attempt to break the ice as it could result in damage. No matter how hard the ice buildup is, you will need to be gentle and take your time.

Furthermore, try using tap water to break down the ice. Once the temperature drops and the ice begins to melt, you can use a thawing object to remove the rest. At the same time, check the air filters. You may need to clean them if they are washable or have to replace them if the are disposable. Plus, check the outdoor unit as well and clean any debris and ice buildup around it.

The outdoor unit needs to breathe to help the unit produce warm air. If it is surrounded by trees, shrubs, etc. dead branches and leaves likely end up inside, complicating the functioning.

If the above steps don’t fix the issue, you will need to get the blower motor checked. You will need to contact a professional for the inspection of the blower motor and other parts of the unit. The blower motor is located deep inside the unit and accessing it is not that easy. Only an expert can tell if it can be repaired or needs replacement.

Faulty Reversing Valve

Another thing that commonly stops a heat pump from starting the defrost cycle automatically is a bad reversing valve. It is the reversing valve that changes the direction of the refrigerant flow to activate the defrost mode in a heat pump. If the valve happens to be stuck or damaged, it will not allow the heat pump to go into defrost mode.

There could be several reasons a reversing valve might malfunction. Sometimes, even new reversing valves tend to malfunction and you are left with no other option but to replace them. Resolving reversing valve issues should only be tended to by a professional.

You have to keep in mind that a heat pump is an electric appliance. Electrical appliances unlike mechanical appliances may not give out any signs & symptoms if there is a developing problem. Plus, they also come with safety features that automatically shut down the unit to protect it.

This means that electric appliances can malfunction due to a variety of reasons leaving you with no clue whatsoever. In some cases, they will either fail to turn on or simply shut down in the middle of the operation. That said, you will need to consult a heat pump repair service Tyson’s Corner who can send a professional to troubleshoot the issue.

Low Refrigerant Levels

Heat pumps require a certain amount of refrigerant to produce cool and warm air. With a low refrigerant level, the heat pump will struggle to produce hot air. At the same time, it might call for a leak as well. Although refrigerant leaks are not common in new units but can occur due to improper installation.

Whereas, in the case of old units, damage, cracks, and wear and tear over time can lead to refrigerant leaks. If the unit happens to be new, you can claim a warranty. However, if the unit is old, you might need to replace it. Heat pumps will last somewhere between 10 to 15 years.

Your tell-tale sign of replacing the heat pump is if the compressor gives up at the same time. Low refrigerant levels directly impact the performance of the compressor and might even burn it up if the situation is ignored.

Then again, you will need to contact an expert to refill the refrigerant. But you need to ensure any cracks, damages, or leaks are fixed first or refilling the refrigerant will go in vain. Refrigerant gas is not cheap and can burden your savings if you are not serious about it.

Improper Installation

If your heat pump is struggling with defrosting and everything else seems to be working fine, it could be that the entire unit was installed incorrectly. For this, the contractor who installed the heat pump is to blame. So, only hire the right people for the job.

Now, if you have recently purchased a new unit, the company will install it for you. However, in some cases, you might have to hire an expert for HVAC installation.

While looking for heat pump installers, you will notice some people who will offer the service at a price lower than the market average. It will be tempting to hire them and save money, but you should not hire them. The best way to hire the right individual is by getting multiple quotes and interviewing the individuals.

Always choose the professional who has the most experience and skills. At the same time, depending on your region, the expert may need to have a license and insurance to perform the installation. In addition to that, it could also be that the unit was installed in an area where the airflow is poor.

To fix the issues, you will need to look around and find someone who has the potential to fix the defrosting cycle as effectively as possible.

Electrical Issues

Electrical issues are fairly common in old units. With time, the wiring can experience wear and tear that could lead to shortages. If that is the case, the heat pump will not receive the signal to defrost. Furthermore, mice, rats, and other animals also are in the hunt for warm places during the winter season.

They could chew and damage the wires which will prevent the unit from functioning normally. Fortunately, fixing a bad wire or wires is not that much of a problem but you should not do it on your own unless you have the expertise. Otherwise, it is better to consult an expert.


Make sure you schedule heat pump maintenance by HVAC companies McLean to avoid repairs and replacements. This will help keep the unit running smoothly for years to come.

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