There are many factors that can cause your AC coils to freeze. Frozen AC coils are usually characterized by a layer of ice on the unit. However, indoor AC units aren't always accessible. In such cases, you'll have to rely on other signs to know if your coils are frozen.
Unexplained condensation and leaks can be a sign of frozen coils, and warm air coming from the supply registers can also point to the same problem. If you're dealing with frozen coils, there are certain steps you'll need to take.
Thaw the Condenser Coils
Before anything can be done, the coils will need time to thaw. This means you'll have to find the controls for the AC in the breaker box and switch them off. This can take up to 24 hours depending on the ambient conditions near the unit.
Once the coils have thawed, clean up the water that will have collected in or around the unit.
Turn the Fan On
The AC fan can be set to run on its own by adjusting the thermostat. Turning the fan on will circulate air through the coils, and this will help to melt any ice that may still be clogging them. You can use a portable hair dryer if you wish to speed this process up. However, you should use the lowest possible heat setting. Too much heat could cause the coils to crack.
Get to the Bottom of the Problem
Thawing out the unit is only part of the problem. You still need to figure out what caused the condenser coils to freeze in the first place. Otherwise, you'll find yourself repeating the same process a short while later. Common reasons why coils freeze include:
Dirty air filters: If the air filters are dirty, air will not be able to enter the AC easily. Without the circulating air, the coils temperature will drop.
Damaged fans: The fan is what pushes the air through the AC. If the fan isn't working or if it has damaged blades, there won't be air circulating in the system.
Blocked condensate lines: The condensate line is used to drain moisture from the system. If this line is clogged, the water inside can freeze especially if the blockage is in a cold part of the AC.
Identifying the exact cause of the problem can be difficult. It's a good idea to look for an air conditioning repair service and let them identify the root cause.