Is Your A/C Freezing Up? Here’s Why

August 22, 2013
Ross and Witmer

Charlotte area homeowners who’ve experienced uncomfortable heat due to an air conditioner¬†freezing up may wonder why it happened and how to prevent it from occurring again. The following quick guide to freeze-ups may help you.

Insufficient airflow
In an efficiently functioning system, warm air passes over a coil containing extremely cold refrigerant, causing condensation on the coil. If dirty air filters and/or undersized ductwork restrict the airflow, the coil’s temperature drops below freezing, causing the condensation to freeze before it can drip into the drain line.

To prevent this problem:

  • Check air filters at least once per month and change them as they begin looking dirty.
  • Clean registers and leave them open.
  • Contact an experienced HVAC contractor to evaluate your ductwork.

Cool temperatures
Cool nights and unusual summertime weather patterns can cause temperatures to drop below 60 degrees-lower than most air conditioners’ temperature optimum threshold.

To prevent this problem:

  • Monitor upcoming weather conditions. Use fans and/or open windows when the mercury dips below 60 degrees.
  • Replace older thermostats with programmable versions.

Mechanical problems
If the above tips to stop your A/C freezing up problems don’t work, you may have mechanical issues.

To prevent these problems:

  • Check the drip pan, especially after a freeze-up or in humid weather when large volumes of water need to drip away. Insufficient drainage may allow the cold coil to freeze the water, causing ice to block the drain hole.
  • Check the fan speed. If it’s too slow, it may not be moving enough air.
  • Have the refrigerant checked by an expert HVAC technician. If it’s improperly charged, if it’s leaking, or if the level is too low, the refrigerant in the coil can’t absorb enough heat to prevent it from dropping below freezing.

If you have any questions about how to prevent A/C freezing up problems, or for information on upgrading to a more energy-efficient unit, contact Ross & Witmer. We’ve been serving the Charlotte area since 1945.

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