Tips on Dealing With Frozen Evaporator Coils


On a hot summer's day, the last thing you need is your air conditioner deciding to call it quits. There are plenty of reasons why this can happen, but the most common reason involves an evaporator coil caked with frost or even solid ice.

A frozen evaporator coil can stand in the way of cooling comfort. The following is a comprehensive guide detailing how freeze-ups can happen, what can be done to fix them and how to prevent them from happening in the future.

What Puts Evaporator Coils on Ice?

Contrary to popular belief, air conditioners don't cool by adding coldness to the air. Instead, it creates cool air by taking away the air's latent heat. This heat is absorbed by the refrigerant traveling within the evaporator coil, where it's transported to the condenser coil to be released to the air outdoors as part of the refrigeration process.

Meanwhile, the air that passes through the A/C system loses its heat, along with much of its humidity. This humidity is condensed out of the air and ends up in the condensate drip pan. While this is going on, the temperature of the evaporator coil surface is just above water's freezing point. If the coil's temperature drops below freezing, it can cause the moisture on the coil to freeze and create frost. In some serious cases, this can cause sheets of ice to form.

There are plenty of things that can cause this to happen:

  • A refrigerant leak or a failure to add the appropriate amount of refrigerant during a charge can cause the evaporator coils to ice over. Both can cause the refrigerant's pressure to drop, lowering the coil's temperature and allowing ice to form.
  • A lack of proper airflow can also cause ice-ups. Without enough air moving through the evaporator coils, the refrigerant can't absorb as much heat as it's capable of. This also causes the coil's temperature to drop, allowing ice to form. This problem is usually caused by excess dust or mold growth on the coils.

Put the Brakes on Ice Formation

The first step of the troubleshooting process involves checking the evaporator coil itself for any ice or heavy frost formation. If there's any ice present, you can use the following strategies to get rid of the ice:

  • Immediately shut down the unit and let the ice melt. This may take several hours, so it's best to try other alternatives first if you're pressed for time.
  • Set the blower fan selector switch on the thermostat to the "ON" position and allow the ice to melt this way. In comparison to the previous option, this may only take a couple of hours to accomplish.
  • If you have a hair dryer or heat gun, you can apply direct heat to the frozen evaporator coil and melt the ice that way. Be careful to evenly distribute heat across the frozen coil and not linger on one spot for too long.

The one thing you shouldn't do is attempt to break the ice apart with sharp tools, as it'll only result in damage to the fragile fins on the evaporator coil.

Correct the Underlying Problem

Next, you should investigate the potential root causes of the freeze-up. For instance, a clogged air filter can cause airflow issues leading to a frozen evaporator coil. Simply replace the filter and remember to have it changed at least every three months to prevent future clogs and maintain good indoor air quality.

If you see any dust or debris on the evaporator coils, carefully clean it with a soft bristle brush. You can also use a foaming no-rinse cleaner to get the job done. You may want to clean the condensate drip pan as well as the condensate drain after cleaning the evaporator coil. If you see mold growth on the coil, you may want to have a HVAC technician professionally clean the coil to ensure there is no residue left.

You should also have your HVAC technician check refrigerant levels and search for leaks within the central A/C system. You can contact some through resources like 


7 July 2015

Streamline Your HVAC System

As a DIY enthusiast, I started doing everything I could to make my household appliances more effective then ever before. I insulated my attic, worked on cleaning the vents around my kitchen appliances, and eventually turned my attention to my air conditioner and furnace. Unfortunately, the process of taking care of my HVAC system was more intense than I had originally anticipated. I realized that I needed to read about air conditioners and furnaces before I started tinkering around. I made this blog to showcase all kinds of different articles that talk about HVAC, so that you can become a more informed homeowner.