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How to Defrost a Frozen AC Unit

Blockages or equipment failures can cause one or more areas of a cooling system to form ice. Ice formation is always indicative of a problem. When you see it, shut down the air conditioner because continued operation risks damage to the compressor. Most issues causing a freeze-up are more affordable to correct than replacing a compressor. You may even resolve minor problems yourself by following the steps for how to defrost a frozen AC unit. The following advice will also help you know when you have a problem that requires a professional technician.

Tools Needed

  • A Flashlight
  • Screwdrivers
  • Towels

Symptoms of a Frozen AC Unit

  • Air blowing out of vents feels warm
  • AC fails to cool the home to the thermostat setting
  • Utility bills jump unreasonably
  • Water leaks appear
  • Condensation on the air handler
  • Visible ice on the evaporator coil
  • Visible ice on the outdoor unit

Step by Step Directions for How to Defrost a Frozen AC Unit

  1. Shut off the cooling function on the thermostat.
  2. Switch the fan setting from “auto” to “on.”
  3. These two steps are always how you begin to defrost a frozen air conditioner. You must stop the cooling action and allow warm air to circulate and melt off the ice. A small freeze-up should melt in a couple of hours. Extensive ice formation may need the fan blowing for 24 hours to remove all ice.
  4. After turning the AC off, prepare to inspect the AC system by gathering the tools. You might need a screwdriver to access the front panel and view the evaporator coil.
  5. Find the compartment near the blower where the air filter is housed.
  6. Open the compartment and pull out the filter.
  7. The filter will probably need to be replaced.
  8. If you see that the filter is heavily soiled, it could be why your AC is freezing up. You may even see ice on the filter.
  9. If ice was present on the old filter, wipe up any moisture before you slide in the new filter.
  10. Check the intakes and vents throughout your home to confirm that nothing is blocking them.
  11. Remove any obstructions.
  12. Open the front panel on the interior unit and look at the evaporator coil.
  13. A dirty evaporator coil prevents the system from absorbing heat and expelling it outside. A freeze up from a dirty evaporator coil will allow ice to form on the coil.
  14. Even if you don’t see ice on the coil, clean it. You can buy an evaporator coil cleaner or call Sanks Mechanical 1-215-960-4803 for AC repair.
  15. Wipe up the dirt and moisture after cleaning and put the panel back on.
  16. Look around the AC unit for other signs of moisture.
  17. Wipe up moisture and look for the source of the leak. A clogged condensate drain is a common reason for drips and puddles.
  18. Go outside and check the outdoor unit for ice or leaks. A leak could be coolant. Coolant leaks require professional service due to being a hazardous substance. Low coolant could also be the cause of the freeze.
  19. As the fan runs, monitor ice melting.
  20. When all ice is gone, turn the cooling function back on at the thermostat.
  21. Switch the fan setting to “auto.”
  22. At this point, the frozen AC is thawed and should blow cool air again.

Have the Professionals at Sanks Check Your AC Unit

Just because you thawed the AC does not mean it won’t freeze up again. The freeze-up itself would have strained the system and increased the risk of a breakdown. For a decade, Sanks Mechanical has performed dependable service throughout the Philadelphia area. To avoid a total loss of cooling in the future, contact us online or call 1-215-960-4803 for AC repair today.

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