Yikes! Your outside air conditioning refrigerant line is covered in ice—which seems crazy in Arizona heat.

So what’s the deal?

Chances are, your indoor unit’s evaporator coil is frozen solid and cold liquid refrigerant is flowing to the outside unit through the refrigerant line (which is why it’s covered in ice).

DO THIS RIGHT NOW: Turn off your AC and turn the fan setting to “ON.”

To help you protect your AC (and your wallet), we'll explain:

 

What causes the evaporator coil to freeze up

An evaporator coil, a group of copper tubes, freezes when the refrigerant flowing through the tubes gets too cold, causing the moisture in the surrounding air to freeze.

A central AC evaporator coil.

So what causes the refrigerant to get too cold? Usually, it’s one of two things: 

  • Low airflow over the evaporator coil
  • Low amounts of refrigerant

What can cause these two problems?

Let’s divide the possible causes into things you can solve right away and things you’ll need a technician to solve.

 

Try these DIY fixes before calling a pro:

  1. Check for a clogged/dirty air filter—A dirty filter reduces airflow over the evaporator coil, causing it to freeze. Check the filter at least once a month and change it if there's a visible layer of dirt.
  2. Check for blocked return vents—Ensure that furniture or curtains aren’t blocking the return vents (the grates where air gets sucked in).  Like closing supply vents, this reduces airflow over the evaporator coil. 

 

DIY tips didn't work? You might have one of these issues...

  • Dirty evaporator coil—Dirt blocks airflow over the evaporator coil, causing it to freeze up. 

Note: This list isn't exhaustive; it’s just a quick overview of common problems. 

Summary: What now?

If you've completed our DIY tips but your AC is still freezing up

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