One of the reasons your AC unit may not be functioning properly is that it keeps freezing up. Minnesota residents know what it’s like to deal with the cold, but your AC freezing has nothing to do with our climate.
Freezing can be seen within the evaporator coil, or on the exterior of the outside unit (the condenser coils), and will appear to be covered in a thin layer of ice due to frost having built up on the refrigerant lines. So you’re probably asking yourself, “what causes an AC unit to freeze up, and what can I do about it?” The culprit is usually one of the following:
- Inadequate airflow – When too many vents are closed or the air filter is dirty enough to block proper airflow throughout the system, an AC unit can freeze up because it can’t work correctly. The buildup of cold air can result in the refrigerant condensing on the coils.
- The setting is too cold – Not all air-conditioning filters and units are intended to run at extremely low temps for prolonged periods or when it’s cool outside. Especially if the outdoor air is below 60℉, the air pressure won’t work correctly. Installing and using a smart thermostat can help you better understand the temperatures you’re using for what periods of time, and adjust accordingly.
- Improper Freon Levels – If your system is too low or too high on Freon (refrigerant), it could cause the temperature of your evaporator to drop, freezing moisture and thus icing up the system. This could be due to a Freon/refrigerant leak that a contractor will need to repair.
What to do When Your AC Unit Freezes Up
Now that you know what may be causing your AC unit to freeze up, how do you go about diagnosing the issue? For starters, check the air filter to ensure it isn’t causing the issue. If it’s clogged, simply replace it and your problem should not persist. Also try unblocking vents. Sometimes household furnishings such as furniture and drapes can get in the way, causing the cool air to be pushed back through the system. Otherwise, it could be a Freon problem (leak) or the fact that you’re simply running the system too long for too long.
Important note: Before a repair can be done, you will need to defrost the system. Run the system with the fan on, but the AC off for 24 hours then call the home air conditioning repair experts at Sedgwick.
For a proper diagnosis as to why your AC unit keeps freezing up, and to get your HVAC system back in topnotch shape, contact the experts at Sedgwick. We have been in the AC business for decades and know what your home cooling system needs so it’s in tiptop shape this summer.
FAQs
Turning the HVAC fan to ON will force it to blow warm air over any frozen coils—which will speed up the defrost process. Make sure it's actually set to ON and not to AUTO. Automatic settings cause the fan to cycle—starting and stopping over and over again. You want continuous, non-stop airflow over the frozen areas.
How do you fix an AC that keeps freezing up? ›
Check out some of the top tips for preventing your AC from freezing up in hot weather below.
- Check Refrigerant Levels. Low refrigerant levels are usually an indicator of a refrigerant leak. ...
- Clean or Replace Your Air Filter. ...
- Inspect the Drain Line. ...
- Keep Your Vents Open. ...
- Ensure the Fan Is Working Properly.
Turning the HVAC fan to ON will force it to blow warm air over any frozen coils—which will speed up the defrost process. Make sure it's actually set to ON and not to AUTO. Automatic settings cause the fan to cycle—starting and stopping over and over again. You want continuous, non-stop airflow over the frozen areas.
Is it bad if your AC unit freezes? ›
Make every effort not to use your ac unit when it's frozen, as this could unduly strain the compressor. Note: The compressor is the most expensive component of your AC. Excessive strain could damage this valuable component leading to a costly repair service call or replacement.
What temperature causes AC to freeze? ›
Air conditioners are graduated to run within an ideal set of temperature thresholds. If you are operating your AC when the outdoor air is below 60 degrees, then the air pressure inside your unit will fall, and this can cause your Central Air Conditioner to freeze up.
How long does it take for a frozen AC unit to thaw? ›
Your AC will take anywhere from an hour to more than a day to completely defrost. It's important to catch it early to prevent further damage to your unit—and, of course, so you're without cool air for the shortest amount of time possible.
Can a dirty filter cause AC to freeze? ›
Many types of HVAC systems require air filters, which are designed to trap and remove contaminants from the air. Unfortunately, a dirty air filter can restrict the airflow through your HVAC system, causing your AC unit to freeze up.
How to tell if AC coils are frozen? ›
Signs You Have a Frozen Evaporator Coil
- AC runs but never cools your home.
- Warm air blowing instead of cold.
- Ice buildup around the coil.
- The thermostat temperature doesn't match the indoor temperature.
- Frozen lines and ice buildup near outdoor units.
- Flooding near drain pan.
Ice forming on an air conditioner may initially draw some concern. However, it often points to a common problem that most AC units experience in their lifetime. A block of ice on the AC system in your home occurs when a component of the condenser isn't getting enough hot air coming in to maintain a proper temperature.
What causes icing in the air conditioner? ›
Insufficient airflow
The refrigerant that removes heat from the air will become cool, causing an icing problem. Solution: Insufficient airflow may be caused due to a dirty air filter, evaporator coil, or fins. Also, the airflow can become restricted due to a faulty fan or blower inside the air conditioner.
If your ac coils are frozen, it's best to turn off the machine and let them thaw out before turning on the ac again.
Can an overworked AC freeze up? ›
Among the potential adverse effects of overworking an AC, this may reduce pressure in the cooling system, causing an AC freeze-up. You can avoid this by not making demands on your AC that it can't satisfy.
How to unclog an AC drain line? ›
Simply attach a garden hose to your drain line, turn it on, and let it run for a few minutes. This should loosen the clog and push it through your drain line. After doing this, you should make every effort to stop an AC drain line clog from coming back.
How do you clean an evaporator coil without removing it? ›
Use the canister of compressed air to blow the dirt and debris loose. A 90º angle works best if you're using high pressure air for cleaning. If you locate a patch of stubborn dirty place, put the air nozzle close to the surface and it should blow the dirty clear.
