What to Do About Ice on Your Outdoor AC Unit

If you find ice on your outdoor AC unit, turn the cooling system off at your thermostat and set the fan to ON. Let the ice thaw completely before turning the AC back on. Never chip or scrape the ice from your unit or pour hot water over it.

The ice is a symptom. Your job is to let it thaw and check a few simple airflow problems. If your AC freezes again after it thaws, call us for AC repair before you keep running it.

Do This First

Before you start checking your AC:

• Set cooling to OFF at your thermostat.
• Set the thermostat fan to ON. If your blower is working, room-temperature air moving across the indoor coil helps it thaw.
• Give the ice time to melt completely.
• Put towels around your indoor unit if melting ice could reach the floor.
• Check your filter and make sure your vents are open and clear.

Do not restart your AC while ice is still on the system.

Why Ice Forms on an AC Unit

Warm air from your house has to keep moving across the indoor coil. If that airflow drops or your system loses refrigerant, the coil gets too cold and moisture starts freezing on it.

As the freeze-up continues, ice spreads from the indoor coil onto the refrigerant line. That is why you may see ice outside even though the problem started inside your house.

The Common Causes

If your AC unit is frozen, we start by looking for the reason the indoor coil got too cold.

• Your filter is clogged. A filter packed with dust cuts airflow across the coil. If yours is packed with dust, start with air filter replacement before you run the AC again.
• Your vents are blocked. Furniture over a return, rugs covering registers, and closed vents restrict airflow through your system.
• Your system is low on refrigerant. An AC system is designed to keep refrigerant contained, so a confirmed low refrigerant charge usually means the system should be checked for a leak rather than simply topped off.
• Your blower has a problem. If it slows down or stops, your system loses the airflow it needs across the coil.
• Your evaporator coil is dirty. A layer of dirt keeps air from moving across the coil the way it should.
• You ran the AC on a cool night. Running your cooling system when outdoor temperatures are unusually low can cause the coil to freeze.

Frozen AC Line: What the Iced Copper Pipe Means

A frozen AC line is another sign to shut the cooling system off. The larger insulated copper line running between your indoor and outdoor equipment carries refrigerant. Ice on that line commonly leads us back to an airflow problem or low refrigerant.

If your filter and vents look good but the line freezes again after your system thaws, do not keep restarting it. If your system is low on refrigerant, we need to find where it is escaping. We will check the damaged area before starting any refrigerant leak repair.

Ice on a Heat Pump in Winter Is Different

If you have a heat pump, some frost on your outdoor coil during an Iowa winter is normal. In heating mode, the outdoor coil gets cold enough for frost to form. Your heat pump periodically runs a defrost cycle to clear it.

If heavy ice stays on the unit, keeps building, or your house is getting colder, have us check your heat pump instead of trying to remove the ice yourself.

Do not chip ice from your heat pump. You could damage the coil or refrigerant lines.

What You Can Fix vs. What Needs a Technician

You can check your filter, open blocked vents, move furniture away from returns, and clear leaves or debris from around your outdoor unit.

Do not open a refrigerant line or try to add refrigerant yourself. That work belongs with a licensed HVAC technician. Blower motors, electrical problems, and coil repairs need professional service too.

During AC maintenance, we check your filter, airflow, coils, and refrigerant operation for problems that lead to freezing.

Call Greens Before It Damages the Compressor

If you find ice on your outdoor AC unit again after it has completely thawed, leave the cooling off. Repeated freeze-ups put extra strain on your system and can damage the compressor.

Greens Appliance, Heating & Cooling has served the Des Moines area since 1958. If your AC keeps freezing in Des Moines, Grimes, or the surrounding area, schedule online and let our technicians find the cause.