Common Causes of an AC Freezing

As summer weather sets in, you want cool air in your home—but there’s nothing cool about cold. A malfunctioning air conditioner often gets a little too cool for its own good and freezes up, preventing the flow of cool air throughout the home. You may think this necessitates an entire new unit, but some appropriate repairs and general maintenance may be all you need to get your air conditioner back to its cool self. The common causes of an air conditioner freezing are usually easy to address.

Dirty Coils

The scourge of dirt and debris on refrigeration coils should be familiar to anyone whose nonfunctioning refrigerator has misled them into thumbing through an appliance catalog for an outright replacement when they merely needed to clean the evaporator coils. As collected debris begins to insulate the coils, the coils cannot function properly, and the refrigerant cools the coils until they freeze the surrounding moisture and develop a block of ice. This puts your entire AC unit out of action. First things first—you’ll have to shut off the unit to thaw out the surrounding ice. Once that has melted, you can get to work with a wire brush and remove the accumulated detritus from around the coils. By keeping your AC unit away from plant life and dirt that can infiltrate the unit, you can reduce the likelihood of this dilemma.

Cool Air in Cool Weather

Running the AC before the heat gets unbearable can seem a little gratuitous. The dehumidifying properties of central air conditioning make it tempting to switch to air conditioning during mild but damp spring or autumn weather, keeping the home’s humidity within comfortably low parameters. But cool and cool don’t always go together when it comes to the AC unit. Insufficiently warm ambient air poses a problem for air conditioners: when the air is too cool, the unit can freeze up. Once you’ve fixed the problem as you would with dirty coils, consider using ceiling fans to circulate and dehumidify damp indoor air instead.

A Dirty Filter

Even during your furnace’s off-season, your air filter needs to stay clean. A dirty air filter reduces airflow and interrupts the heating and cooling cycle, which is integral to proper AC unit function. Just as with dirty coils or cool ambient air, improper circulation causes the AC to go into overdrive until it freezes up. A dirty filter is the most common cause of an AC freezing, but it’s the easiest to remedy. Replace your filter with a clean model—we recommend the high-MERV–rating varieties of AAF Flanders air filters—and get back to enjoying life at room temperature all summer long.

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