How to Stop Your AC From Freezing

It's a hot summer's day in Northern Virginia, and suddenly your AC stops working!

You walk outside and take a look at your AC to find that it's covered in ice! You've got yourself a frozen AC system.

Not to worry, all you have to do is turn it off and leave it to melt.

That should fix it. Right?


The problem actually starts inside, on your indoor coil. Your coil is probably covered in ice, and it'll take hours to melt it off. Until it's thawed out, you won't be able to get any air through the cooling coil.

Turning it off for a short while and turning it back on will cause it to freeze up again. So always look into the cause of a freezing AC before you switch it off.

Today we're going to take a look at what causes air conditioning units to freeze in Northern Virginia and what you should do if your unit freezes.

Help, my AC is frozen! Can you defrost an AC unit?

Generally, if your AC system has frozen, you'll have to thaw it overnight for about 5-8 hours due to the amount of ice that can build up. You have to be incredibly careful when thawing your AC because it can drip down on the furnace and burn out some of the furnace's components when the ice melts.

You already have to worry about a freezing air conditioning unit, and you don't want to add a damaged furnace into the mix.

After melting the ice, homeowners are often under the impression that the problem is fixed when the AC starts working again. They cancel their service call before their technician arrives and are delighted they managed to fix their AC themselves.

Yay, no technician fee!

But then it stops working again!

They have to call the technician again, which delays the necessary repairs and extends the time they have to spend in an uncomfortable, overheated home.

What causes a frozen AC in Northern Virginia?

If you ever see ice on your AC, you should call for help from a trained technician as air conditioner units can freeze for a number of reasons.

These reasons include:

Dirty air filters

If your air filter is dirty, then you won't have enough air flowing across the coil, and it'll start to ice up.

Low on refrigerant

When the refrigerant drops in a unit, the surface coil temperature also drops. It becomes so cold that the water that's being removed from the air freezes.

The surface gets blocked with ice, and that ice starts building up. It works like the ice maker in your refrigerator, so ice is always a potential problem.

Restricted airflow 

If you have furniture or other debris blocking a floor vent, you will be restricting the airflow, which can cause it to freeze. 

Setting the temperature too cold

Having your temperature set to the lowest it can go for long periods of time can cause your system to freeze over.

The AC system is too big for the home

If your AC unit is too big for your home, then it's going to be blowing too much cold air through your home, which can lead to it freezing over.

What to do if you can’t find the cause of your frozen AC?

If you can't see any obvious reason that your airflow is being restricted, then you should:

  1. Call your air conditioning contractor
  2. Turn the AC system off and let it thaw out before your service technician shows up
  3. Don’t turn the AC back on until your technician arrives and assess the situation

Don’t leave your AC running when you call a technician

One of the biggest issues that we have with frozen units is people call for help and think it's okay to leave their air conditioner running so they can have a bit of cool air while they're waiting.

This is not a good idea!

No air is getting through to your home if everything is frozen. If you leave your air conditioner running, then you might actually burn up your air conditioner. This will leave you with a more expensive problem to fix.

Remember, your system will still be frozen with ice when your technician arrives if you leave it running. This means it'll be impossible to work with, and the technician will reschedule.

We want to help make sure your AC works perfectly, so make sure you thaw out your AC unit before your call in a technician to help you.

A healthy system relies on good airflow, which is why you should always let an expert team of technicians take care of your unit.

Our team of skilled HVAC technicians in Northern Virginia can help fix your air conditioning unit and help prevent future, expensive repair jobs. If you need any help with your HVAC system or have any questions or concerns, contact us today.