What Causes My AC To Freeze Up and How Can I Fix It?

It sounds counterintuitive, but an AC freezes up when it gets too cold. Specifically, the refrigerant in the coils drops below freezing. If there isn’t enough warm air blowing over those coils to balance it out, the humidity in the air turns to ice, and suddenly, you’ve got an igloo in your furnace closet.

So, if your AC has turned into a giant popsicle, don’t reach for a hair dryer just yet. Here’s the “why” behind the frost and how you can get things flowing again.

1. Restricted Airflow

This is the “clogged nose” of HVAC issues. Your AC needs a constant, steady stream of warm indoor air to keep the coils from getting too chilly.

• The Culprit: A filthy air filter. If air can’t get through the dust, the coils just sit there getting colder and colder until they freeze the condensation right off the air.
• The Fix: Change that filter! Also, make sure you haven’t closed too many supply vents in unused rooms; the system needs to breathe.

2. Low Refrigerant

It sounds backwards… shouldn’t less coolant mean less cold? Actually, low refrigerant causes the pressure in the system to drop. When pressure drops, the temperature of the remaining refrigerant plummets.

• The Culprit: A leak. Refrigerant doesn’t just “run out” like gas in a car; it’s a closed loop. If it’s low, there’s a hole somewhere.
• The Fix: This is a job for the pros. They’ll need to find the leak, patch it, and recharge the system.

3. A Tired Blower Motor

If the fan isn’t spinning fast enough (or at all), that warm air we talked about isn’t reaching the coils.

• The Culprit: A bad motor or a failing capacitor. If the fan isn’t pushing air, the cold just stays put.
• The Fix: Listen for the fan. If the outside unit is humming but you don’t feel air coming out of the vents, your blower motor might be on strike.

I’m Frozen. Now What?

If you see ice, stop running the AC immediately. Continuing to run it can actually kill the compressor (the most expensive part of the whole system).

The 3-Step Thaw Plan:

1. Turn it OFF at the thermostat: Switch the setting from “Cool” to “Off.”
2. Switch the Fan to “On”: Change the fan setting from “Auto” to “On.” This will blow unchilled air over the ice to help it melt faster.
3. Check the Drain Pan: As that ice melts, it’s going somewhere. Make sure your condensate drain isn’t clogged, or you might end up with a small flood.

Contact American AC Heat Plumbing For All Your AC Needs in Los Angeles, CA and the Surrounding Areas

A frozen AC is usually a cry for help regarding airflow. Check your filters first, let it thaw completely (which can take a few hours), and try again. If it freezes right back up, it’s time to call in the cavalry. Hi, that’s us! American AC Heat Plumbing is here for all your cooling needs in Los Angeles, CA and the surrounding areas. Contact us today!