To troubleshoot the cause of your air conditioner freezing up, it’s a good idea to first understand ow the air conditioner works in the first place. The AC unit requires proper airflow to keep the cold coil warm. This warm air comes from inside your home and helps ensure the temperature stays above freezing. Without it, the coil can freeze before the condensed water can be drained from the AC.
So, why is your AC unit freezing up? More than likely, something is preventing the warm air in your home from transferring its heat into the AC unit. This causes the coil to drop below freezing, which results in the AC freezing up. Alternatively, something could be making your Freon expand more than required, making your coil colder than they should be. The result? You’re left with an icebox.
Below, we’ll detail the possible causes that you can check and rule out. You can find out what causes an air conditioner to freeze up.
1. You’re Using Your AC in the Wrong Temperature Range
“What causes an air conditioner to freeze up?” is always the question on many homeowners’ mind. There are actually lots of possible reasons why this happen. By design, air conditioners are meant to be used when the air outside the home is above 62 degrees.
If you run your AC unit when the temperature is below this number, the pressure inside the system will inevitably drop, leading to a freeze up.
2. Your Thermostat Is Set Too Low
If you have an older AC unit or a unit that’s too small for your home, you might need to set the thermostat very low in order to get it to cool moderately well. If you’re the type of person who likes the home to be very cold, you might lower your thermostat.
Unfortunately, setting the thermostat too low, it can cause the system to get too cold and the moisture that’s condensing on the coil to freeze. Setting the thermostat to fan can help thaw the coil.
3. You Have a Mechanical Failure
Whether it’s a kink in your refrigerant lines or a blower fan that’s out of balance, there are several different types of mechanical failures that could occur within your AC system that could cause it to freeze up.
A damaged blower fan, in particular, is a common cause of an AC freezing up. This fan is critical to the system because it helps move the warm air out of the home. A damaged blower fan will negatively affect the airflow inside the air handler. This can cause condensation buildup on the coils that can’t drain properly.
It’s also possible for a damaged blower to cause the refrigerant line to freeze too, which can cause even bigger headaches.
4. The Coils Are Too Dirty to Function Properly
Maintaining your AC unit can help ensure it doesn’t freeze up because, often, the cause of a dirty air conditioner coil.
The coil is not only used to cool the air in your home but also to dehumidify it. The coil pulls water out of the air, which results in a condensation buildup on the coil. In a properly functioning unit, the condensation droplets would fall off the coils and into a drip pan. But if your drip pan is too full, the coils can become waterlogged and dirty.
The dirt on the coil will ultimately prevent it from absorbing water at a fast enough pace, which can cause freezing. With regular air conditioner repair and maintenance, you can ensure this doesn’t happen.
5. There Is a Lack of Air Flow
If you have a split air conditioning unit, which is the most common type of AC, the system is designed to take heat from your home and transfer it outdoors to cool your home. If the unit isn’t functioning effectively and the warm air from inside the home isn’t being blown over the evaporator coil, then you’re not going to get any heat exchange. As a result, your Freon won’t be removing any heat form the home.
Over time, the temperature will drop more and more because there won’t be enough heat to prevent condensation on the coil. Eventually, the coil will turn to ice.
When the problem is lack of air flow, you should look at your air filters to determine whether they’re clean or need to be replaced. You can also check the air vents in your home to feel for air leaks. Also check for closed or blocked grates, closed dampers, and blocked ducts, which could be causing the air flow problem.
6. The System Is Low on Refrigerant
You could be low on refrigerant due to lower pressure inside your AC unit. This pressure change can change the physical properties of the refrigerant and cause it to act differently. When your low on refrigerant, but the system is still expecting the Freon to expand the same amount, your coil will drop below freezing. The moisture in the air will condense and freeze once it moves over the coil. Ice will then begin to form.
This will begin as a light frost, which you may not even notice. But over time, more and more ice will form, which will cause the refrigerant to evaporate faster and prevent the AC from functioning properly.
Then, the ice may melt, but that won’t solve your problems. You’ll notice that the system won’t cool your home anymore due to water damage. It will need to be repaired in this case.
Proper AC maintenance can help prevent many of these problems.
