Finding your air conditioner iced over in the middle of summer seems unlikely, but happens more than you’d think. The more humid the air is, there is actually a greater chance of finding a frozen condenser.

There are 5 main reasons your AC is freezing up:

1.Low Refrigerant

The #1 most common culprit is low refrigerant. Lacking refrigerant can cause the coils to get too cold and ice over. This is because a normal level of refrigerant creates pressure and that pressure heats up the evaporator coils. When levels drop, there is less pressure and therefore, a lower temperature within the coil. This allows water vapor to attach to the coil and freeze. It may start out as a small frost but can eventually turn into solid ice.

2. Blower Fan Not Working

A related issue could also be that your air conditioner’s blower fan is not working properly. The blower fan is in charge of pushing warm air to the coils. If it becomes damaged, this will prevent air from moving through your AC system correctly and make it hard for the coil to stay warm.

3. Other Airflow Problems

Air conditioners need a good, constant flow of air so that water from the humid air can’t freeze on the coils. While the blower fan not working is definitely an air flow problem, there are also other common airflow blockers.

  • The number one culprit of lacking air flow is a dirty filter. Turn off the unit and give it time to defrost. Once it is defrosted, check the filter and replace it if it’s dirty. Then wait a couple hours to see if system operation improves. READ MORE: Recommendations on how often to change your filter.
  • Make sure all your indoor registers are clear and open. You may need to move any furniture or other items that are blocking vents. Also, check your rooms for vents that are shut and open any supply vents.

4. Dirty Evaporator Coil

The final major cause of an AC freezing is a dirty coil. The evaporator coil inside your air conditioner cools the air inside your home, but it also dehumidifies it. By doing so, it pulls water from the air and that water can cause condensation that builds up on the coil. Besides this, as your home’s indoor air travels in and out of the unit, so does the dust and particles it carries from your ducts. This dust can settle on your coil. Getting regular AC maintenance can help to avoid this issue as the coil should be cleaned with each tune-up.

5. Air Duct Problems

All of the air in your HVAC system moves through the air ducts throughout your home. This passage of air is necessary for proper HVAC system operation. If there is a leak or large blockage is your ductwork, then this could result in poor enough airflow to cause your AC unit to freeze. If you notice weak airflow coming out of your vents along with ice on your system, it is possible the culprit could be inside the ducts. You can schedule a free air duct inspection or duct cleaning with Quality Comfort or another reputable contractor to put a camera into your ductwork to investigate the issue further.

Important: What to do before calling for service

If you have gone through all the steps above and your AC still is not blowing cold air, call a professional AC service company to assist. Before calling, make sure to turn off your air conditioner at the breaker so that it will be thawed by the time the technician arrives and they will be able to diagnose the problem more quickly. You can expect it to take 1-3 hours to thaw depending upon the amount of ice buildup on the unit. Shutting down the air conditioner also prevents further damage to your AC if there is an issue with the fan or coil. Do not try to run your air conditioner while ice is present as it could cause the need for expensive repair.

What not to do

Do not attempt to break up any ice buildup using something sharp. You could easily damage parts of the system and cause a need for further repair.