If you see ice on your indoor or outdoor unit, it is a clear sign that there is something wrong with your AC unit.
The worst part is if you keep running the AC, you risk damaging the compressor— $1,495+ AC repair (more on that later).
- Turn the thermostat from COOL to OFF
- Turn the fan setting to ON
- Check your filter and replace it if needed. If the filter isn’t dirty, call a professional before turning the AC back on.
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 will explain the rationale behind each of the steps above. We will also provide help tips that will prevent expensive water damage, or a busted AC unit.
Your AC is freezing up for a reason, and simply thawing out the unit won’t fix the root problem. If you want to solve the problem at the core, we can help. Just contact us.
Step 1: Turn the thermostat from COOL to OFF
With ice being on the AC unit this means the refrigerant, the liquid that cools your home’s air, is much colder than it should be. If that cold refrigerant is sent to the outdoor unit, it could kill your compressor. The compressor should only 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 a healthy operation, your compressor should only receive refrigerant in the form of a superheated gas—NOT a cold liquid.
Step 2: Turn the fan setting to ON
By turning the fan on it 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: Do not turn your fan setting to AUTO. This setting only runs the blower motor during a cooling cycle. Furthermore, 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 your AC unit to thaw?
It can take up to an 1 hour or 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, you should 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 dirt picked up along the way can form a clog in that drain line and cause water to backup and overflow. If you think you have a clog, please follow these steps in this blog to clear the condensate drain line.
The most common culprit behind a frozen AC is a dirty or 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 identical to the filter below, then change it out for a new filter immediately.
Believe it or not a thin layer of dust or 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. Also when your air conditioner doesn’t get enough warm air flowing over your evaporator coil, the refrigerant inside will colder and colder. Remember: very cold refrigerant coils + moisture in the air = ice.
You replaced your dirty filter, so now what?
Since you just replaced a dirty filter you will continue to wait until your AC has completely thawed out. Once your AC is unfrozen go ahead and turn the AC back on and run the air normally, but keep a close eye on the unit for the next couple of days.
More than likely, the dirty filter was the problem, but to be sure that there isn’t another issue watch for any ice returning on the AC lines. If you notice any ice forming or notice other AC problems, call a professional 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 is completely clean, you have a more serious AC problem regarding:
- 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 you see ice on your indoor or outdoor unit, it’s a clear sign that something’s wrong with your AC unit.
Please do not ignore this problem, or you’ll continuously deal with a frozen AC and you will end up paying over $3,000 for a damaged compressor.
For repair on your AC, call our technicians today. We also provide heating repair for your furnace or heat pump.