Troubleshooting And Solving Problems With Frozen Air Coniditoners

If your air conditioning unit freezes up, you may automatically think it is because the thermostat was set too low. While that is a logical conclusion, there are other issues that can cause your AC to freeze. If your air conditioner freezes on a holiday weekend and you can't get service right away, you may be able to take care of the problem on your own. Look for these common reasons for a frozen air conditioner.

Blocked Air Flow

Your air conditioner needs a steady flow of air to work properly. If the airflow inside your home is constricted, or blocked, your air conditioner may freeze.

  • Check for objects blocking the AC. Children may sit toys down in front of the unit, furniture may be moved or your drapes may have fallen over the air conditioner and stopped the airflow. Move the objects and keep the space in front of you air conditioner clear.
  • Check the air filter. The air filter in your air conditioner is designed to filter out dust, hair and pet dander to keep the air in your home clean. It generally does a good job of this task; in fact, it does its job so well that it may become clogged with dust and debris. If the air filter to your air conditioner is dirty, replace it with a new filter. Media filters on air conditioners should be changed once or twice a year. If you have pets or live in a dusty area, you may need to change it more often.
  • Check your ductwork. Vents and ductwork can also get dirty and restrict the air flow to your air conditioner. Use the brush attachment on your vacuum cleaner to vacuum dust and hair from the vents. Spray a paper towel with all-purpose cleaner and wipe away any remaining dirt or dust from the vents. For seriously clogged vents, remove the vent cover or grill and use the crevice tool to vacuum dust from the vent.

Dirty Evaporator Coils 

The evaporator coils inside your AC unit are filled with coolant. As warm air passes over the coils, the coils absorb the heat from the air and recirculate the cooled air. During this process droplets of water form on the outside of the coils and are drained away either through a catch basin or directly outside the home. If the coils become coated with soil, the dust and dirt works to insulate the coolant and causes the water droplets to freeze. If you suspect that dirty coils may be your problem, you will need to de-ice the unit and clean the coils.

De-Icing Your Air Conditioner

You may be tempted to get out the hammer or chisel to knock the ice off your AC unit, but this isn't a good idea. Pounding or striking the unit can cause serious damage to your air conditioner. Here's what you need to do to de-ice it.

  1. Turn off the air conditioner.
  2. Turn off the power to the air conditioning unit. Look for the main switch that controls your air conditioner in your breaker box and turn it to the off position.
  3. Let the air conditioner thaw naturally. It may take up to 24 hours for it to thaw completely. If you are in rush, you can speed it along by using a hair dryer set on the lowest setting.
  4. Wipe down the coils with a clean, soft cloth once they have thawed. They will likely be covered with drops of water. If dirty coils were the cause of your problem, you will probably find a layer of dirt and grime on the coils, too. Make sure you remove all the dirt or dust when you wipe down the coils.
  5. Turn the power back on to your AC unit and turn the AC back on.

If these remedies do not solve your problems with a freezing air conditioner, call your local HVAC dealer who specializes in air conditioning repair. He can identify and correct more serious problems for you.