Why is My Air Filter Frozen?

If your air filter is frozen, it is apparently clear that something is wrong with your AC unit. The only reason you would notice your air filter is frozen is if you happen to be checking on it, replacing it, or cleaning it, which is a great thing to be doing. However, if your air filter is frozen, then odds are you will find that part of your indoor or outdoor unit is frozen as well somewhere, and there will be literal ice. In the case you see some ice somewhere on your unit, you have to address it immediately, otherwise you risk serious, permanent damage which will end up costing you more in the long-run. Please do not be naive to think that this does not happen in the peak heat of summer—it ironically is more prone to freezing during this time of the year as it is when the AC is working its hardest.

The hot temperature outside has no effect on the inner workings of the AC unit and its ability to suddenly freeze—humidity, however, can make things even worse. If your AC unit is frozen, you will have to thaw it out—yep, just like that chicken you just took out of your freezer for dinner tonight. It’s pretty simple for you to unthaw the part of the unit that is frozen, but this is not exactly a permanent fix as the freezing happened for a reason. You will still have to make sure that you address exactly what is causing your unit to freeze in the first place. If there is visible ice on your unit then that means your refrigerant, the liquid that cools the air within the unit and your home, is colder than it should be. If this too-cold refrigerant reaches the part of the unit outside, then you risk it damaging the compressor—the part of the system that compresses the refrigerant to get the pressure and temperature right when cooling. The compressor can only receive refrigerant in the form of a hot gas, not a cold liquid. You have to keep the compressor happy and working as this is one of the most expensive parts of the unit to replace or fix.

How to fix a frozen air filter:

The process of unthawing is simple for the most part. You’re going to want to turn the thermostat from “Cool” to “Off.” This will obviously turn your unit off for the time being and prevent the cold refrigerant from continuously making its way to the compressor outside or throughout the rest of your unit. Next you are going to turn the fan setting on. The fan setting is usually right there next to the “Cool” and “Off” settings on the thermostat. You will most likely hear the fan come on. The fan setting turns the blower motor on which will start blowing warm air throughout your system and over the frozen refrigerant coils—which make up the evaporator coil—of the unit which will speed up the unthawing process. The process of thawing out the unit can be lengthy sometimes, so be patient.

As it thaws, the drain pan, which is located near the refrigerant coils, may start to leak water. If you have access to the indoor part of your unit, put some towels down so a puddle does not start to form. Don’t try to break up the ice with a tool or your hands to prevent any puddles from forming or to speed up the process, it can cause even more damage. As the ice begins to melt, it will flow towards and through the condensate drain which is usually a white pvc pipe. Keep an eye on that pipe to make sure a clog caused by dirt isn’t forming which will cause backup and overflow. Once the thawing out process is underway, quickly go check the air filter of the unit to see if it needs to be replaced. In most cases, the problem of the frozen unit is caused by an issue with the air filter.

You are going to want to check the filter quickly after you start the thawing out process in order to avoid a dirty puddle that you will have to clean up from it starting to melt. If the filter is damaged or dirty you must deal with it immediately. It is best to play it safe when it comes to the filter. Even if there is only a thin layer of dust, you should change it to avoid any further problems. When the filter is dirty, it prevents enough warm air from getting to the evaporator, which causes the refrigerant to get too cool. Make sure you confirm the exact filter that is needed before changing it. Every home and unit requires a different type of filter. If the filter was visibly dirty or damaged and you have successfully changed it, wait for the entire unit to be thawed out before turning it back on.

Once you have turned the unit back on, keep a close eye on it for the next few days to ensure it is running nicely. In the case that your air filter does not need cleaning, nor looks as though it is damaged, it is time to call a professional. If the air filter was fine, then there is something more serious wrong with your AC unit. This bigger problem could be a refrigerant leak, dirt on the evaporator coil, a weak blower motor, or a number of other things. The only thing you can do is call a professional. Do not try and fix anything on your own, or just ignore it, because then it could cause lasting damage to either your house, or your bills. One of the best things you can do for yourself and your unit is schedule regular maintenance checks to make sure everything is working right. This may seem like an unnecessary, added expense, but preventative care can only help you in the future.

If you need a new air filter, check out Filter King’s online store!