If you see ice on either your indoor or outdoor unit, it’s a clear sign that something’s wrong with your AC unit.
The worst part? If you keep running the AC, you risk damaging the compressor—a $1,495+ AC repair (more on that later).
That said, follow these steps to unfreeze your AC unit quickly:
Note: These instructions will simply help your AC to unthaw but won’t guarantee the prevention of further damage due to falling ice chunks, water on controls, water damage, etc.
In this article, we’ll explain the rationale behind each of the steps above. We’ll also provide tips that will help you prevent expensive water damage, or worse—a busted AC unit.
Step 1: Turn the thermostat from COOL to OFF
Ice on the AC unit means the refrigerant, the liquid that cools your home’s air, is much colder than it should be. And if that abnormally cold refrigerant is sent to the outdoor unit, it could kill your compressor. The compressor should only ever receive refrigerant in the form of a superheated gas—NOT a cold liquid.
Here’s the bottom line: Turning the thermostat from COOL to OFF stops your AC from continuously sending cold refrigerant to your outside unit (where your compressor is located).
During healthy operation, your compressor should only ever receive refrigerant in the form of a superheated gas—NOT a cold liquid.
Want more in-depth information about why your AC is freezing up in the first place? Just check out our blog, “Why Is My Air Conditioner’s Refrigerant Line Covered in Ice?”.
Step 2: Turn the fan setting to ON
Turning the fan to ON forces your AC’s indoor fan to blow warm air non-stop over your AC’s frozen coils. This will help the ice thaw faster.
Tip: Don’t turn your fan setting to AUTO. This setting only runs the blower motor during a cooling cycle—and remember, you just turned the thermostat from COOLING to OFF so your AC won’t be going through any cooling cycles.
Your AC blower motor pulls in warm air from inside your home and blows it over the refrigerant coils that make up the evaporator.
How long will it take for my AC unit to thaw?
It can take anywhere from 1 hour to over 24 hours to unfreeze your air conditioner. It all depends on the extent of the ice buildup.
As you’re waiting for the unit to thaw, keep an eye out for:
- An overflowing drain pan. If you can access your indoor AC unit, you may want to put some towels on the floor surrounding the unit. This will help prevent water damage if the melting ice overflows the drain pan and leaks onto the floor.
- A clogged condensate drain. As the ice on your evaporator coil thaws, the water will drip into a condensate drain pan and then flow outside via a condensate drain line (a white PVC pipe). Sometimes, though, dirt picked up along the way can form a clog in that drain line and cause water to back up and overflow. If you think you have a clog, follow the steps in this blog to clear the condensate drain line.
Step 3: Check your air filter and replace it if needed
The most common culprit behind a frozen AC is a dirty/clogged air filter. So, check your air filter as you wait for the unit to thaw out.
Pro tip: Check your filter as soon as you turn the thermostat to OFF. The longer you wait, the more likely the ice will melt onto your air filter and create a dirty puddle.
If your air filter looks similar to the filter below, change it out for a new filter immediately.
Even a thin layer of dust/dirt on your air filter can cause major AC problems, so change it out even if the filter isn’t quite as clogged as the one above.
A dirty air filter “suffocates” your air conditioner. And when your air conditioner doesn’t get enough warm air flowing over your evaporator coil, the refrigerant inside gets colder and colder. And remember, very cold refrigerant coils + moisture in the air = ice.
Need help finding your air filter? Check out our blog, “Where Is My Air Conditioner Filter?”.
I replaced my dirty filter, now what?
If you just replaced a dirty filter, continue waiting until your AC has completely thawed out. Once your AC is unfrozen, turn the AC back on and run the air normally but keep an eye on the unit for the next few days.
The dirty filter was most likely the problem but to ensure that there isn’t another bigger issue, watch for any ice returning on the AC lines. If you notice any ice forming or notice other AC problems, call us at (602) 842-0009 to inspect and diagnose your unit.
Step 4: Don’t have a dirty filter? Call a professional right away
A dirty air filter isn’t the only problem that can cause a frozen AC—but it’s the only problem that you can solve on your own.
If you checked your air filter and it’s completely clean, you have a more serious AC problem, such as:
- A refrigerant leak
- Dirt on the evaporator coil
- A weak or bad blower motor
- Stuck or closed expansion valve
- Collapsed duct
- Any other number of AC problems
And don’t ignore this problem. Otherwise, you’ll keep dealing with a frozen AC and eventually you’ll end up paying over $3,000 for a damaged compressor.
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