Why Is There Ice on My Air Conditioner?

June 13, 2017

Even on a hot summer day, ice can form on your air conditioner. One common symptom of a frozen AC is lukewarm air coming from the supply registers. If you notice this problem, learn why there’s ice on your air conditioner and what to do about it.

Reasons Ice Is Forming on Your AC Unit

Several issues could be causing this problem. Here are the most likely culprits:

  • A low refrigerant level can make the evaporator coil too cold, causing ice to form. Leaky refrigerant lines or an undercharged system could be to blame.
  • A dirty air filter could result in low airflow to the evaporator coil. An insufficient flow of hot air over the coil could allow it to freeze.
  • Closed supply registers could reduce airflow through the system so dramatically that the air conditioner freezes up. Make sure you keep at least 80% of your home’s supply registers open to prevent ice on the air conditioner.
  • An insufficient fan speed could be another reason for poor airflow and a frozen evaporator coil.
  • Thermostat problems may keep the air conditioner running all night, even when it’s cold outside. The relatively low outdoor temperature could reduce hot airflow over the evaporator coil enough that ice forms.
  • Drainage problems can prevent condensation from dripping off the evaporator coil and draining away. If something blocks the condensate drain, the backed-up water can freeze on the evaporator coil. Then, the ice blocks the drain and makes the problem even worse.
  • An improperly tilted window air conditioner fails to drain properly. When condensate sticks around inside the unit, it can freeze.

How to Handle Ice on Your Air Conditioner

  • Shut off the AC to prevent risking damage to the compressor.
  • While you wait for the ice to melt, locate the condensate drain and make sure it isn’t blocked.
  • If necessary, open up the ductwork and suction out water with a wet-dry shop vac.
  • Use a blow dryer on the evaporator coil or set the thermostat fan to “on” without running the air conditioner to speed up the melting process.
  • For a window air conditioner, tilt the unit outward slightly so melting ice drips outside. This is the proper operating position for window AC units to prevent ice buildup in the future.
  • Once the ice melts and the condensate drain is clear, turn the air conditioner back on. If a frozen evaporator coil was the only problem, the unit should start cooling off your home immediately.

How to Prevent Ice on an Air Conditioner

  • Have the refrigerant level checked.
  • Change the air filter once a month.
  • Keep your supply registers open.
  • Have a technician increase the fan speed.
  • Have a technician check the thermostat for problems.
  • Inspect the condensate drain weekly for blockages.
  • Make sure any window units you have are tilted correctly.
  • Schedule AC maintenance with Rick’s Heating & Cooling once a year.

Call Rick’s Heating & Cooling for Air Conditioner Maintenance & Repair

To learn more about preventing ice on your air conditioner, or to schedule a visit from an experienced cooling technician, please contact us today. We have over 30 years of experience serving Cincinnati and the surrounding areas.