Why Is Ice on My Central AC?

Believe it or not, even in sunny Tampa, air conditioners can and do freeze—especially in the middle of summer when we use them most.

Have you noticed that your home isn’t as cool? Or can you see ice on your AC unit?

Here’s why: Ice forms on your air conditioner because of 2 main reasons...

1. Airflow Issues
2. Refrigerant Leaks

We’ll go into both of these causes and discuss what you can do to stop your AC from freezing over.

But FIRST, let’s look at what you should do if your AC is frozen:

If Your AC Is Frozen, Thaw It out with These Steps

1. Turn Your AC OFF
2. Make sure your AC’s fan is set to ON (normally it’s set on “AUTO”).
3. Put towels around your indoor unit (to prevent water damage from melted water).

DON’T turn your AC back on until you find the root problem. Otherwise, you may damage your AC.

Now that we got that preliminary caution out of the way, let’s look at what’s causing your AC to freeze...

Frozen AC Cause #1: Airflow Issues

Your AC system is constantly moving your home’s warm air to the evaporator coil where it uses liquid refrigerant to cool that air and return it to your home.

Now, if there’s not enough air flowing over the evaporator coil, the refrigerant will drop below freezing. Then, when the warm, humid air comes into contact with the cold refrigerant, the moisture freezes.

Some common AC problems that restrict airflow include:

• Dirty and Clogged Air Filters
• Blocked Return Vents (Or They’re Too Small)
• Closed Supply Vents
• Improperly Sized or Blocked Air Ducts
• Filthy Evaporator Coils
• A Malfunctioning Blower Fan

Frozen AC Cause #2: Refrigerant Leaks

If you have insufficient refrigerant in your AC system (caused by leaks), then the pressure drops, which lowers the refrigerant temperature even further. The colder refrigerant freezes the condensation on the coils.

When the ice finally melts, you may notice a significant amount of drainage around your indoor AC unit.

To know if you have a refrigerant leak, look for these signs:

• You Hear a Hissing or Bubbling Sound Around Your AC.
• Your Electric Bills Are More Expensive.
• It Takes a Long Time for Your Home To Cool Off.
• You Have Warm or Lukewarm Air Coming From Your Air Registers.

What You Can Do to Stop Your AC from Freezing Over 

DIY Solutions

A clean air filter vs. a dirty air filter.

If your air filter looks like the one on the right, it’s dirty and you need to change it.

A return vent.

• Unblock your return vents: Make sure there are no drapes, furniture, or objects within 2 feet of your return vents.

A supply vent.

• Open supply vents: Keep these vents open, even in rooms you don’t use regularly. This will keep air flowing properly in your AC system.

Issues a Professional Needs to Solve

If none of the above DIY fixes work, you’ll need to call an air conditioning technician to check if you have these problems:

• Dirty Evaporator Coils
• Return Vents That Are Too Small
• A Malfunctioning Blower Fan
• Blocked or Improperly Sized Air Ducts

Live in the Tampa Area? Need Help from a Florida Tech?

Contact Red Cap Air to schedule an AC repair. One of our air experts will get that ice off of your AC and fix whatever’s causing it to freeze so you’ll have a working AC in no time!