Frozen AC – The whys and what to do about it

It’s strange yet common for AC systems to freeze in the summer. Several problems can contribute to a frozen system.

  • Insufficient air flow: A common problem that we’ve found in Colorado is the outside unit is covered in cotton from the cottonwood trees and is blocking air flow to the condenser.  Restricted air flow can also be caused by a furnace filter that is too dense or too dirty.  A dirty evaporator coil (the unit on top of the furnace) will cause freezing and you’ll get water pooling under the furnace.
  • Low on refrigerant: Refrigerant in the AC system can dissipate over time and cause pressure drops that will allow the moisture in the air to freeze and accumulate on the evaporator coil.  You may also have a leak in your refrigerant line.
  • Thermostat setting:  Freezing on the outdoor unit can occur when you’ve got the AC running and it’s cool outside.  If the temperature outside is lower than the temperature you’ve got set on your thermostat, the outside unit may freeze.

So your AC is frozen and is just blowing warm air. What can you do?

  • Turn your thermostat to fan only: The AC system needs to thaw and the fan will help it to do that.
  • Check the furnace filter: If your filter is dirty, replace it with the least expensive, least dense filter to allow for maximum air flow.  Same thing goes with a dense HEPA type filter.  They restrict air flow.
  • Check the outside unit: Clean off any debris such as cotton, leaves, dirt.  These can be hosed off.
  • Thermostat settings: Make sure that you are not running your AC when it’s cool outside.  If you’ve got a programmable thermostat, set it for a warmer temperature at night.

When you’ve exhausted all of these options (or your just not a fix it yourself kind of person) and your AC is still not working well it’s time to give us a call.

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