Frozen Evaporator Coil – What to Do

Frozen evaporator coils are never a good sign, even during the summer. They can be an indication that something is wrong with your air conditioner, and ignoring the problem can likely cause your compressor to burn out.  

Luckily, you may be able to fix the problem yourself before shelling out for expensive repairs. Here are some steps you can take if you think there is a problem with your air conditioner: 


  • Check for ice around the outdoor refrigerant line. 
  • Look around your air handler for condensation and moisture. 
  • See if your condensate drain pan is full or overflowing. 
  • Open your air handler and check for ice or condensation on the evaporator coil.  


If you see any of these signs, it is important to address the issue as soon as possible. If you have frozen evaporator coils, the first thing you should do is turn off your system at the breaker box. While you are inspecting the possible causes and fixing them, your coils should be able to defrost completely. 


Once the coils have defrosted, it is recommended to contact your local HVAC technician to come and inspect your coil professionally. Your technician can check for any damage to the coil or other parts of the air conditioning system that may have been caused by the frozen evaporator coil. It is always better to be safe than sorry when it comes to your HVAC system, so don’t hesitate to call in a professional if you are unsure about any aspect of your system’s operation. 


Common Causes of Frozen Evaporator Coils


Dirty Evaporator Coils

Dirt and debris buildup on the evaporator coils, which are responsible for transferring refrigerant to the heat pump, can cause your system to work harder to condition the air. This can lead to an increased risk of your evaporator coil freezing. To ensure proper heat absorption, it is important to clean the coils regularly. Failure to do so can result in freezing and other costly issues. 

Refrigerant Issues

Refrigerant should not need to be replaced unless there is a leak somewhere in the system since it operates in a closed system. However, leaks due to normal wear and tear can occur and go unnoticed for extended periods. When refrigerant levels are low, your HVAC system is forced to work harder than necessary, which can cause ice to form on your evaporator coils. This can result in decreased efficiency and even cause your system to break down over time. Therefore, it is essential to have your system checked regularly by a professional to ensure that refrigerant levels are appropriate and to identify and address any leaks as soon as possible.

Airflow Issues

A frozen evaporator coil could be the result of improper airflow from your blower. There could be several reasons for this issue, but the most common cause is a clogged air filter. When your air filter is clogged, it restricts the airflow, which results in reduced air circulation through your HVAC system. This reduced airflow can cause the evaporator coil to become too cold and ultimately freeze over. It’s important to regularly change your air filter to avoid this issue and maintain proper airflow throughout your system.

  • Additional reasons for inadequate airflow include:
  • Improperly sized filter
  • Damaged or improperly sized ductwork
  • Closed vents and blocked return grills
  • Dirty air handler and/or heat pump
  • The fan or blower motor isn’t operating properly.

Drainage Problems

Your evaporator coil is responsible for removing humidity from the air, especially in humid conditions. As the humidity decreases, condensation forms and is drained from your home. However, if your drainpipe becomes clogged, the water may back up and freeze on your evaporator coils. This can worsen the problem as the frozen condensation further restricts proper airflow, causing your system to work harder and potentially leading to further issues with your air conditioner. To avoid these issues, it’s important to regularly inspect and maintain your drainpipe and evaporator coils to ensure proper function and prevent any potential damage. 

Indoor and Outdoor Temperatures

When the outdoor temperature drops below 60 degrees, the performance of your heat pump and air handler may be compromised. If the air conditioning is running in cool outdoor temperatures, the evaporator coil may freeze over. This happens because the refrigerant temperature becomes too low and the moisture in the air freezes on the coil. If you notice ice buildup on your evaporator coil during colder weather, it’s best to turn off the A/C and wait for the coil to defrost before turning it back on. 


To prevent the inconvenience and expense of frozen coils and the additional problems they cause, it’s important to keep your HVAC system in good condition. One of the best ways to do this is by signing up for a bi-annual maintenance plan like the Whole Home Maintenance Plan or the Budget Savings Club. With these plans, trained technicians will inspect and clean your system twice a year, ensuring that any potential issues are identified and addressed before they turn into costly problems. Plus, with regular maintenance, your system will operate more efficiently, reducing your energy bills and extending the lifespan of your equipment. Contact us to learn more about our maintenance plans and how we can help keep your HVAC system running smoothly year-round.


HEATING, COOLING & Plumbing Specialists

Providing 5-Star Service in St. Louis, MO.

HEATING, COOLING & Plumbing Specialists

(636) 887-2800: Call or Text


325 Mid Rivers Mall Dr. St. Peters, MO 63376


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