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Troubleshooting And Thawing A Frozen Air Conditioner

If your air conditioner seems to be on the blink and isn't cooling the air in your home, there may be a simple reason. Sometimes, a layer of ice builds up on the air conditioner coils. While it may seem like that would produce even cooler air in your home, it doesn't work that way. If your air conditioner freezes, it loses the ability to filter and cool the air inside your home. Here's what you need to know to troubleshoot the problem and restore your AC to good working order.

Why does ice form on the air conditioner?

There are three common reasons why your air conditioner may freeze. The most common is restricted air flow. That means clogged filters or vents may be preventing the air from your home from circulating over the evaporator coils adequately. Other common reasons include low refrigerant and a faulty blower. While they each require a different remedy, they all require thawing the coils first.

How do you know what's causing the freezing?

Before you thaw the coils on your air conditioner, you need to assess whether the freezing is due to airflow issues, low refrigerant or a mechanical problem so you will know what to do after the coils thaw.

  • Blower Malfunctions

Check that the blower on your air conditioning unit is functioning. If the blower is working, check for airflow problems.

  • Airflow Obstructions

  1. Check your filters and vents for any debris or obstructions. This includes curtains or household furnishings that may be obstructing air flow into the vents in living areas. It also includes dirt and debris clogging your unit from the outside.
  2. Change or clean the filters and remove any objects that may be contributing to reduced airflow.
  • Refrigerant Levels

If the blower is working and there are no obstructions to the airflow, it is likely that your air conditioning unit is low on refrigerant. Call your HVAC contractor from a company like Aggressive Mechanical Contractors if you suspect this is the problem.

How to you thaw air conditioning coils?

 Thawing the coils is not difficult, but it may take several hours.Thawing needs to be done regardless of the underlying cause of freezing.

  1. Disconnect the air conditioning unit from the electrical source.
  2. Apply gentle heat to the coils with an hair dryer set on the warm setting. Using the hot setting may crack the coils. Slow, warm heat will speed the thawing without posing a risk to the unit.
  3. Alternately, you can allow the air conditioning unit to sit until the ice is melted. This may take several hours, depending on the outside temperature and the amount of ice built up on the coils.
  4. Wipe down the coils with a soft cloth to remove excess water and moisture when the ice melts.
  5. Plug the air conditioning unit in and set the thermostat controls to fan only to allow air to circulate and melt any remaining ice.
  6. Set the thermostat to cooling once the ice has melted, providing you have identified and corrected any airflow issues. Your air conditioner should now blow cooled air into your home.


  • Never use a sharp object or hammers to remove ice from your air conditioner. This can cause damage to the unit.
  • Always disconnect the unit from the electrical source while removing ice or wiping away moisture.
  • Turn the AC unit off and leave it off while you wait for a serviceman. Running the unit while the coils are encased in ice can burn out the motor of your air conditioner. In addition, the HVAC repair person cannot service the unit until the ice has melted.

Troubleshooting and correcting airflow issues often solves the problem with a frozen air conditioner and is a good first step to identifying the problem. If you are unsure or uncomfortable with working on your unit, call the repairman, but don't forget to turn the unit off and let the coils thaw before he arrives.