It’s a hot summer day, and your air conditioner seems to be losing some of its cooling power. You go to check out the unit to see if anything is wrong, and you see ice on the evaporator coil. “Oh!” you might think, “Well my air conditioner must be working if I see ice. After all, it’s a sign the air conditioner is cooling.”
This is a misconception. Ice on the evaporator coil is not okay, and is a sign you need AC repairs sooner rather than later.
The Sign of a Problem
As we alluded to above, ice along the evaporator coil of your air conditioner indicates that something is wrong with the AC. For reasons we’ll get to below, your evaporator coil is staying cooler than it is meant to, and this causes the moisture that condenses on it to freeze.
This starts a vicious cycle, since ice on the coil makes it harder, if not impossible, for the refrigerant inside the coil to absorb heat and raise its temperature—only compounding the problem. If the coil freezes over completely, your cooling system won’t be able to provide you with cool air at all!
Reasons Icing Occurs
One reason you may have ice developing on the evaporator coil is due to a refrigerant leak. There’s a common misconception among homeowners that it’s normal for air conditioners to lose refrigerant, and the AC needs to be refilled every maintenance appointment. If an inexperienced handyman told you this was the case, we apologize on their behalf.
The truth is an air conditioner is supplied with enough refrigerant upon installation to (ideally) last its entire lifespan. So if it’s losing refrigerant, it means that there is a leak, and we already told you what that could lead to.
The second reason ice might form on the coil is due to a clogged air filter. Again, we’re going to mention a misconception. Maybe you’re one of those people who believe the air filter that comes in your HVAC system is there to protect your indoor air quality. But, while a clogged air filter won’t exactly help your indoor air quality, that’s not its purpose anyway.
The air filter is in place to protect the inside components of the air conditioner itself, from dust, lint, and other debris. This debris has to get caught somewhere, however, and that’s where the air filter comes in. What happens though, if you don’t change or clean this air filter every 1 to 3 months, is it won’t let in a sufficient amount of air for the coil to cool, which triggers the freezing process.
One last reason an evaporator coil might freeze over is the coil itself is covered in grime. A dirty coil—one covered in a layer of dirt or dust—will be insulated enough that it cannot properly absorb heat, and ice will develop.