One of the most frustrating issues you can encounter during the summer is your AC freezing up and your house quickly starting to get unbearably warm. There are really only a few reasons why an AC will freeze up.
Sometimes, the problem is something you can fix without needing to call an AC repair professional if you know what to check for. This article will explain the issues that can lead to an AC freezing and also what steps you need to take if your AC is frozen.
Insufficient Airflow
Even though the refrigerant is typically well below 0 degrees when it first enters the AC evaporator coil, frost and ice usually don’t form on the coil. Under normal circumstances, the warm air continually flowing across the coil results in it staying at around 40 to 50 degrees Fahrenheit. The refrigerant also quickly gets hotter as it captures heat from the air, which also helps prevent the coil from getting cold enough that it freezes.
If the airflow is restricted for any reason or the blower otherwise isn’t drawing enough air in, the refrigerant won’t capture as much heat and can quickly make the coil so cold that frost forms and the condensation on it freezes. As soon as this starts to happen, the coil will continue to freeze more and more until it basically becomes a solid block of ice.
The most common cause of restricted airflow is an overly dirty, clogged air filter. Clogged or obstructed return vents can also restrict the airflow to the point that the evaporator coil freezes. If you find that your AC keeps freezing up, these are the first two things you should check.
If the blower is coated in a thick layer of dust or beginning to wear out, it will often not be able to pull in enough air to keep the coil from freezing. Some homes also just don’t have enough return vents for the blower to draw in sufficient air.
Dirty Evaporator Coil
One of the most important parts of professional AC maintenance is cleaning the evaporator coil to remove all of the dust that naturally collects on it. A dirty evaporator coil can greatly hamper the AC system’s performance and cause a substantial decrease in energy efficiency.
Not only that, but it will also often lead to the system freezing up. What happens is that the layer of duct essentially creates a blanket that blocks the warm air from flowing directly over the coil. This greatly reduces the amount of heat the refrigerant can capture, causing it to stay cold enough that the coil begins freezing up.
Luckily, this issue is something you can easily overcome by having a technician clean the coil. It’s also a good idea to have them clean the condenser coil as well, since this will also help your AC to cool much more effectively and work more efficiently.
Refrigerant Leak
A refrigerant leak is another issue that can result in an AC system frequently freezing up. The refrigerant continually changes pressure throughout the refrigeration (cooling) cycle as its temperature changes.
The problem when an AC system has a leak and is low on refrigerant is that it causes the pressure to be lower than it should. This results in the refrigerant getting much colder than normal. That means that it can make the evaporator coil cold enough that it freezes even if there’s enough warm air blowing across it.
Refrigerant leaks can occur because the evaporator coil or condenser coil is damaged, which is one reason you should never try to clean the coils yourself. The coils or the copper lines can also develop pinhole leaks due to corrosion.
Fixing a refrigerant leak is a costly and time-consuming process, and especially so if either coil is damaged and needs to be replaced. After pinpointing the location of the leak, the technician will need to depressurize the system by capturing all of the refrigerant.
They’ll then need to recharge the system and add more refrigerant once they’ve fixed the leak. If you have an old AC system that uses R-22 refrigerant, it often isn’t worth fixing the leak due to how incredibly expensive this type of refrigerant is now.
How to Tell if Your AC Is Frozen
In most AC systems, you usually won’t be able to directly check if the evaporator coil is frozen due to the air handler being fully sealed. Nonetheless, you will usually know quite quickly when your AC freezes up, as it will start blowing warm air out of all of the supply vents.
If you notice that your AC is putting out warm air, you should go outside and look at the outdoor unit. In most cases, you’ll also see frost on the copper line right where it enters the unit.
What to Do if Your AC Freezes Up
Any time your AC freezes or you suspect it’s frozen, you should make sure to immediately turn it off. One reason is just to prevent more ice from forming, but the biggest reason is that the compressor can potentially burn out if the system continues running.
The refrigerant is normally a gas when it enters the compressor. If the system is frozen and the refrigerant can’t capture heat from the house, it will remain a liquid. The concern when liquid refrigerant enters the compressor is that it will quickly boil, which can cause the oil in the motor to boil and burn off.
This can then lead to the motor not being sufficiently lubricated and seizing up, in which case you’ll typically have to pay at least $1,000 if not much more to have the compressor replaced.
While you should switch your thermostat from cooling mode to off if your AC is frozen, you should also switch the fan from the auto setting to On. This way, the blower will keep running and blowing warm air over the evaporator coil so that the ice melts and the coil thaws more quickly.
It will usually take a couple of hours before the coil completely thaws and it’s safe to turn your AC back on. However, it could take up to 24 hours if the coil is extremely frozen and covered with a thick layer of ice.
While you’re waiting for the coil to thaw, you should check to see how dirty the air filter is and if it needs to be replaced. You also want to make sure that all of the supply and return vents are fully open and not clogged or obstructed.
It’s also a good idea to put towels down on the ground around the air handler. Sometimes, the melting ice can overwhelm the condensate drain, resulting in the drain pan overflowing and water leaking out of the air handler.
Once you’re sure that the coil is fully thawed, you can try running your AC again. However, if the issue wasn’t a dirty filter or blocked vents, there’s a good chance the coil will quickly freeze again. As such, it’s a good idea to call for a professional inspection and monitor the temperature of the air coming out of your vents in the meantime so that you can tell if the coil starts to freeze again.
Call Us Today
At Liberty Comfort Systems, we’re here 24/7 to help you with dependable your air conditioning services and heating solutions. We’ve been serving Anoka and the surrounding areas since 2004 and are proud to be recognized as one of the area’s premier HVAC companies.
Our NATE-certified technicians service and repair all brands of HVAC equipment and will make sure to properly fix whatever issue you find yourself facing. To schedule an inspection and get help determining why your AC keeps freezing, contact us today.
