Here’s What to Do When Your AC Unit Freezes Up: How to Defrost it (IMPORTANT Steps!)

The weather’s getting hotter, but your AC unit isn’t getting colder. How can that happen?

It turns out, your AC unit has frozen up. Most people don’t actually know the reason why AC units freeze up, especially in the summer.


Don’t worry! This is a common problem with easy solutions.

Here’s what to do when your AC unit freezes up.

What a Frozen AC Unit Means

A frozen AC unit may resemble a freezer. Its exterior or interior may be covered with ice, sometimes all the way down to the AC pipe.

For the exterior, the ice can come out looking like shaved ice or sharp icicles. Internal freezing looks a lot more like snow inside the unit. For either condition, it almost looks as if your unit has battled a snowstorm.

Ways to Unfreeze or defrost Your AC unit

Once you’ve checked all signs that your AC unit is really frozen, it’s time to work on how to unfreeze it.

Method 1: Thaw Your AC Unit

The first step is to turn your AC unit off completely, including the electrical breaker. This ensures that your AC unit gets no electrical currents.

Once turned off, you’re in the waiting game. Wait until the ice on the AC unit’s evaporator coils defrosts. This could take several hours up to a whole day, depending on how frozen it is.

If the evaporator coils are still frozen after a day, don’t turn your AC on yet. Using it while the coils are still frozen can pose more harm than good to your unit.

Double check where your AC condensate line runs as this can cause problems if it is not properly installed.

Method 2: Dry Your Coils

If thawing doesn’t work, try drying your evaporator coils.

Run the thermostat on your AC unit and set it to fan mode. The thermostat should have a higher temperature than your room. The circulating air will quicken the drying process. Check the manual of your device to make sure that your manufacturer recommends the same procedure.

When your coils are dry, you should have your AC back to how it was before.

Method 3: Call a Trusted HVAC Technician

If your AC unit still freezes up after thawing your coil, you may need to call a technician. This can also be your chance to give your AC unit a general “check-up.”

An HVAC technician should be able to determine the underlying problems of your freezing AC unit. Pinpointing the source of the problem can prevent more serious damages and save you money in the long run.

Reasons Why Your AC Unit Freezes Up

It can get irritating when your AC unit freezes up the moment you really need it. Why do they actually freeze, though?

Here are some common reasons why AC units freeze up:

Blocked Airflow

Blocked airflow is the most common reason an AC unit freezes up. AC units rely on a constant airflow to function properly. When the airflow gets blocked, it puts pressure on the unit to operate normally.

Blocked airflow can also cause humidity to build up inside the unit, which contributes to the freeze.

Blocked airflow can easily be fixed by cleaning your air filters, which are affordable and easy to change. What’s more, they can improve your AC unit’s efficiency by up to 15%.

Mechanical Problems or Leaks

Sometimes, parts inside the unit can stop working because of wear and tear. As a result, your AC can suffer from a drop in pressure, which brings up the temperature of your refrigerant.

Refrigerants tend to leak when they’re hotter, lowering refrigerant levels. When refrigerant levels drop, the refrigerant becomes less pressurized, which may cause your AC line to freeze up.

You can identify leaks from your AC unit by observing how much water accumulates in your

AC’s water collector. This large volume of water could be caused by melting ice from the evaporator coils or a damage in your condensate drain.

Cold Summer Nights

AC units are set to operate within a strict range of optimal temperatures. When colder nights during the summer fall out of this range, your AC unit can run into some problems.

To fix this, you can invest in a programmable thermostat. This thermostat eliminates the risk of overworking your AC unit when the temperature outside is too low.

How To Prevent Your AC From Freezing Up

You can prevent your AC from freezing up by following these simple tips:

Change Your Filters

Regularly inspecting and replacing your air filters can make a world of difference in the performance of your AC unit.

It’s generally recommended to check your filters at least every couple of months. There’s no strict timeline on when you should change them, but most people replace them every three months.

Of course, this time can vary depending on several factors like:

Type of filter

Kids or pets at home

Dusty climate

Smoking member at home

Family member with health conditions

Frequency of system runs

If you’ve got kids or pets at home, it’s better to change your air filter every two months. You can even change it more frequently if your kid has any allergies or respiratory conditions.

Living in a dusty climate or with a smoking member at home can also clog your filters faster. If any of these apply, you may want to consider changing your filter every month.

Check Your Coolant Levels

Checking your coolant levels requires a schedule with your HVAC technician. They usually perform a complete inspection of your AC unit, including checking your coolant levels.

You can identify a low coolant level if your AC unit does any of the following:

-Produces a hissing sound

-Takes time to cool

-Blows hot air

Even before any of these signs happen, you should still schedule a maintenance appointment to prevent any serious damage to your AC unit.

Clean Evaporator Coils

Having clean evaporator coils is one key to preventing your AC unit from freezing up. If there’s clogging within the condensate lines, water gets stuck and freezes the coil.

Evaporator coils can also get clogged with dust or grimes. If they get clogged with moisture, your coils can freeze up and restrict airflow out of your AC unit.

To clean your coils, you can call for a technician or clean them on your own. Of course, you’ll be more assured that your coils will be clean if a technician does it.

In Conclusion

A frozen AC unit is a common problem for many homeowners. This doesn’t mean it can’t be avoided, though. Getting a new AC system can be expensive so you should try to fix it if possible.

Understanding why your AC unit can freeze up can be your guide to preventing significant damages. With some regular cleaning and maintenance, your AC unit can surely provide you with a cold breeze on a hot summer day.

We have discussed how you can handle AC water leaks here.