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There’s Ice on My AC Coil, but the Filters Are Clean — What’s Wrong?

Frozen air conditioning unit outside of home.

A dirty air filter is one of the most common causes of ice forming on an AC coil. But it’s not the only reason, and there could be several other issues, some of which could be serious.

If you have ice on your air conditioning unit, shut it off and let it defrost so you can troubleshoot the problem. Since a frozen AC unit can significantly decrease the equipment’s efficiency, it’s usually best to call a professional to inspect and repair it.

The skilled team at Raleigh Heating & Air is equipped to handle all your HVAC needs, including air conditioning repairs, replacements, and maintenance. Our AC services are designed to put your needs first and keep your Raleigh, NC, home comfortably cool.

How AC Coils Work

Your air conditioner’s coils work in tandem with the refrigerant to keep your Raleigh home cool. As the refrigerant transforms from a gas to a liquid, it’s pressurized and then moves into the coils. Once there, it changes back to a gas by pulling in air from the surrounding environment.

After the air cools, it’s blown through your ducts and into your home. Once your home reaches the temperature set on the thermostat, your AC unit will shut off. The cooling cycle resumes once your home’s interior warms up again. The process is typically complication-free, but once in a while, the unit has a malfunction or breakdown that can cause ice to form on the coils.

Why Ice Forms on AC Coils

 Common causes of AC coil ice buildup include:

  • Low refrigerant: This is often the first sign of a leak in the AC unit. As the system’s pressure lowers, so does the temperature, which can cause ice to form on the evaporator coil.
  • A dirty evaporator coil: This can cause ice to form because airflow through the unit is restricted. A dirty coil can also damage the compressor, as the unit uses more electricity.
  • Mechanical failures: Issues like broken valves, bad wiring, damaged fans, blocked drains, or kinked refrigerant lines can all cause a central cooling system to freeze.
  • Dirty air filters: This typically causes airflow restriction that results from a frozen system, leaks or clogs in the ductwork, closed vents, or something blocking the outdoor unit.

The best way to deal with these AC issues is to have your system inspected and serviced each spring. That way, you’ll catch potential problems before they become expensive repairs or replacements.

AC Repair for Frozen Coils

When you notice ice on your coils, check your air filters. If they’re clean, your best solution is to call a professional HVAC service provider. Don’t try to scrape the ice off the coils, as you could damage them. Plus, it won’t solve the underlying problem.

Once the issue is resolved, some simple maintenance can keep your AC system performing as it should:

  • Change the filters every one to three months, depending on use and dust accumulation.
  • Hire a professional to clean the coils once or twice per year.
  • Know the signs of low refrigerant and address the issue early.

Raleigh Heating & Air is committed to keeping the stress out of maintaining your home’s AC system by offering:

Don’t wait for a minor AC issue to become a major problem.

Contact us online or call 919-635-8451 to schedule services with one of our licensed AC experts.

Raleigh Heating & Air, Inc. provides air conditioning service to Apex, NC, and throughout Wake County and the surrounding areas. We have the finest people in the industry, and every worker is inspired to elevate your experience.

Raleigh Heating & Air