A frozen evaporator coil is a fairly common AC problem that can result from a few different issues. Warm air blowing out of all of your vents when your AC is running is the first and really the only obvious sign that can indicate that the evaporator coil is frozen. When ice builds up on the evaporator coil, the AC system will no longer be able to cool. The ice prevents the warm air coming into the system from contacting the evaporator coil, which means the refrigerant can no longer capture heat from the air.

If you do notice that your air conditioning system starts blowing warm air and the temperature in your home is starting to rise, you can be almost certain that your AC is frozen as this is generally the only issue that will ever cause the system to blow warm air. If your AC is frozen, it is important that you follow these steps both to help the system thaw more quickly and to prevent any possible damage that could occur.

1. Turn the AC Off

The very first thing to do if you notice warm air blowing from your vents is to immediately shut the AC off by switching your thermostat setting from “Cool” to “Off.” There are several reasons why you never want to leave your AC running when the evaporator coil is frozen. For starters, there is simply no point in leaving it on since it can’t cool and will waste energy.

Another reason is that the ice on the coil will continue to become thicker the longer you let the system continue to run, which means that it will take much longer for the system to thaw once you do shut it off. All that said, the biggest reason you should immediately shut your AC off is that severe damage can occur and result in the outdoor AC condenser unit burning out and forcing you to have the entire unit replaced.

When your AC is working properly, the refrigerant absorbs enough heat as it flows through the evaporator coil that it changes from a cold liquid into a hot gas. When the system is frozen and the refrigerant can no longer absorb heat, it can lead to the refrigerant remaining in a liquid state as it flows out of the coil and moves back outside.

If liquid refrigerant enters the compressor in the outdoor unit, it can cause some of the oil in the compressor motor’s crankcase to burn off. If too much oil burns off, the motor will no longer be properly lubricated and can seize up and burn out. This is a major issue as the compressor motor cannot be repaired. The motor can be replaced, but the cost of replacing it will usually be about the same as installing a new AC unit. This is why it’s absolutely essential that you turn your AC off as soon as you notice it starts blowing hot air.

2. Switch the Fan On

While you want to make sure to shut your AC off, you may want to change the fan setting on the thermostat to “On” instead of “Auto.” Switching the fan to the “On” setting will make it so that the fan continues to run even though the AC is off. This means that the fan will continue to pull warm air in through the return ductwork and draw the air over the evaporator coil so that all of the ice starts to melt more quickly. If you leave the fan shut off, you may need to wait for half a day or more before the coil fully thaws and you can use your AC again.

3. Replace the AC Air Filter

A dirty, clogged air filter is the most likely culprit any time an AC system freezes. As such, the next thing you’ll want to do is replace the AC air filter. If your home has a furnace, the air filter is most likely located in the supply duct just next to the furnace. If not, the other possibility is that the filter is located behind the return air vent where air is drawn into the system. When replacing the filter, it is important that the arrow on the filter points in the direction that air flows through the system, towards the furnace, or else the filter won’t work properly, and lots of dust and debris will get sucked into the system.

When the air filter isn’t changed regularly, it can become clogged so that very little air can flow through it. This results in much less warm air coming into the system and blowing over the evaporator coil. When there isn’t sufficient warm air blowing over the coil, the refrigerant will remain much colder, and the condensation that naturally forms on the coil can start freezing.

4. Place Towels in and Around the Air Handler to Soak Up the Water

If there is lots of ice on the evaporator coil, all of the water that results when it starts thawing can often be more than the AC condensate drain system can handle at one time. This can lead to the drain pan becoming full enough that it overflows and water starts to leak out everywhere. As such, it’s a good idea to place towels on the floor around the air handler to soak up any water and prevent possible water damage. You may also want to open the access door on the air handler and put a few towels underneath the drain pan and evaporator coil for the same reason.

5. Wait Until the Evaporator Coil Is Completely Thawed

The next step is simply to wait for however long it takes for all of the ice to melt and the evaporator coil to completely thaw, which will usually take a couple of hours. You can try to use a hair dryer to speed up the process, but you should definitely never use anything like a torch to thaw the coil or try to chip off or break the ice off as this can damage the coil and lead to a refrigerant leak.

6. Turn Your AC Back On and Wait to See If It Freezes Again

Once all of the ice has melted, you can then turn your AC back on. However, it is important that you monitor it for the next few hours or even the next day or so to make sure that it doesn’t freeze again. If it now runs without freezing, you can be fairly certain that the problem was caused by a dirty air filter. If the system does freeze again, you should then shut it back off and leave it off until you can have a technician from Modern Heating and Plumbing inspect it.

In this case, the system could be freezing because the evaporator coil is dirty and needs to be cleaned or because of a malfunctioning or failing blower fan that can’t draw sufficient warm air into the system. Another possibility is that the refrigerant level is too low because of a leak in one of the copper refrigerant lines or in the evaporator coil or condenser coil. None of these issues are things that you can repair or really even diagnose on your own, so it’s important to enlist the help of a certified AC technician.

At Modern Heating and Plumbing, our technicians are always ready to help if you’re dealing with an AC that continually freezes or has any other issues. We repair all AC brands and models, and our team also specializes in all types of heating and cooling installation and maintenance services. Contact us today to schedule an AC inspection or any other HVAC or plumbing service in Beach Park or the surrounding areas.

company icon