Why Is My AC Freezing Up?



Although many love the summertime, it is nice to know you have a cool getaway from the heat waiting for you inside your home in Dover, Delaware and surrounding areas. To ensure the comfort of air conditioning is waiting for you at home, it is important to make sure your unit is running properly. A common homeowner repair in the summertime is a frozen air conditioning unit. Many do not understand how 80 degrees and above can allow your condenser to freeze up, but trust us - it is possible! In this blog, we will answer the common homeowner question of "Why is my AC freezing up," and how to proceed.


To understand why your air conditioner is freezing up, let's start with the basics. Your AC unit's main parts are a compressor, evaporator coil, condenser coil, and refrigerant. Each plays a vital role to maintain your comfort. Your air conditioner collects all the warm air from your home, which blows over the evaporator coils. The refrigerant is found inside both condenser and evaporator coils and works to remove heat and moisture. If warm air does not reach the refrigerant, it becomes so cold that the excess moisture on the coils freezes. Your air conditioner is freezing up because of lack of airflow to your coils, where your refrigerant lies. Fix your airflow and you will no longer have a frozen air conditioner.


In most cases, you are able to defrost your AC unit by yourself. Switch your thermostat to the "off" setting and turn the fan setting to "on." These two steps will power off your air conditioner and help blow warm air over the frozen coils. However if there is frost on your fans, skip switching your fan setting on due to possibly delaying the process. Dethawing your air conditioner can take up to 24 hours, so make sure you are prepared to maintain comfort in another way. While the unit is defrosting, try to find the source of the problem. We have listed common reasons your air conditioner froze in the section below. After your air conditioner has thawed, turn your air conditioner back on and monitor it closely. Give us a call if the problem arises again to identify the issue!


It sometimes seems like your air conditioner picks the hottest and most humid day to need repairs. Here are the common reasons for air conditioners to freeze up:

  • Dirty Air Filters
  • Clogged Drain Lines
  • Faulty Blower Fan
  • Low Refrigerant
  • Blocked Air Vents

Dirty Air Filters

Your air filter can be the reason your air conditioner has many problems. Debris such as pollutants and dust can clog your air filter and make it difficult for air to flow through. If the outside of your air filter vent has dust, it is likely your air filter needs to be changed. Airflow begins with your air filter, so start here if your air filter is frozen.

Clogged Drain Lines

While your air conditioner removes heat, it also removes moisture. Moisture exits through a copper or PVC drain line pipe typically near your outdoor unit. Drain lines can become clogged by a buildup of mold, mildew, and debris. If your drain line is blocked, water can become trapped near the evaporator coil and freeze.

Faulty Blower Fan

The blower fan is designed to blow warm air to the coils. If the blower fan is damaged or malfunctioning, there is a lack of airflow and your air conditioner can freeze.

Low Refrigerant

Low refrigerant is a common cause of a frozen air conditioner due to the coil pressure. Low refrigerant leads to low pressure, which allows moisture in the air to accumulate and freeze on the coil. If your air conditioner is low on refrigerant, there is likely a leak which should be addressed by a professional.

Blocked Air Vents

You should not be closing or placing furniture over your air vents. Your airflow will decrease and can cause problems such as air duct leaks and frozen air conditioner coils. Avoid obstructing air coming out of your vents to prevent a frozen air conditioner.

If your air conditioner is not frozen due to any of these issues or continues to freeze, give us a call at (302) 653-4073! We are not comfortable until you are and can help solve any issue with our air conditioning services in Clayton.