What to Do When Your AC Freezes Up

AC Frozen in Charlotte, NC

While many people find it odd that an AC unit can freeze up in the middle of a hot summer, this problem is actually fairly common. There are several reasons why your AC may freeze, and you need to know what to do in case that happens. A few tips on what to do may save you money by avoiding an AC repair.

How to Know If Your AC Is Frozen

One of the most common signs that you have a frozen AC is visible ice on the outside of the AC compressor. However, you may have freezing that is not so easy to see. Another common sign of this issue is warm air blowing from the vents. This is an indication that the evaporator coils are frozen and not allowing for the proper cooling effect.

Common Causes of Freezing in AC Units

The main reason for freezing in AC units is inadequate airflow. Reduced or inadequate airflow in the AC unit can be a result of several things. The freezing could be caused by:

  • A dirty evaporator coil
  • Refrigerant leaks
  • Dirty air filters
  • An airflow obstruction

Once you have established that your AC unit is frozen, it’s important to follow a few steps to fix the issue and find the cause so that it doesn’t happen again. The following covers what to do with a frozen AC unit.

Turn Off the AC and Switch on the Fan

Once you notice that your AC is frozen, turn it off. It does not matter the severity of the ice buildup. With the unit off, turn on the blower and allow the fan to run until the ice in the unit defrosts and dries. Defrosting may take anywhere from an hour to a full day depending on the severity of the freezing. Only turn on the AC after the entire system is dry.

As the AC unit defrosts, you can carry out an investigation to establish the cause of freezing. That will ensure that you take the necessary measures to prevent freezing in the future.

Inspect the Motor and Test the Efficiency of the Blower

While the unit defrosts, the fan should operate efficiently for optimum results. It is important to check the efficiency of the blower as it could be the cause of freezing. The blower is responsible for the circulation of air in the AC unit. Thus, an inefficient blower will fail to circulate sufficient air through the return air inlet. That makes it hard for the AC unit to draw in or spit out air, resulting in freezing due to the cold air from the unit.

Lack of airflow in the evaporator chamber causes freezing as the cold refrigerant in the coil condenses any humidity in the evaporator chamber. Therefore, the AC unit needs a flow of sufficient warm air, which is only possible if the blower is efficient.

The motor of the fan is also a crucial component in ensuring sufficient airflow. You need to check the motor to ensure it is in good condition for efficient output. A hot motor, which indicates burnt components, needs to be replaced.

Clean the Filters

Once you have checked and confirmed that the blower and motor are in good condition, inspect the air filters. First, check the air filter that is between the return duct and the HVAC unit. Next, check all the air filters in the return and supply vents in the house. Ensure that there is nothing that would prevent airflow in the supply and return vents as it would restrict air circulation in the unit. For those with ductless systems, you need to check the filter on the air handler unit.

During the inspection, check for clogs and damages. Dirty disposable filters should be replaced, and dirty reusable filters should be cleaned and reinstalled. We recommend regular checks on the filters, preferably on a monthly basis. The frequency of filter changes varies based on the:

  • Type of filter
  • Presence of pets in the house
  • Amount of pollen in the area you live
  • Presence of household members with allergies or asthma
  • Presence of smokers in the home

Open the Dampers and Supply Vents

After checking and cleaning or replacing filters, you should move on to the dampers and supply vents. The dampers in the supply ducts need to be fully open. Check the dampers and ensure that they are not fully or partially closed. Be sure not to overlook vents in lesser-used rooms. If any of these are closed, they need to be open to ensure proper airflow and HVAC system pressure.

Clean and Remove Obstructions From the Ducts and Vents

For the AC unit to function optimally the ducts and vents need to be free of obstructions. Obstructions restrict airflow and may cause freezing. Therefore, check to ensure that the return vents in the house have nothing blocking their airflows, such as furniture or drapes.

A buildup of dust and debris may also obstruct airflow in the HVAC unit. Thus, ensure you clean the vents and ducts to remove any dust or debris buildup.

Unclog the Condensate Line

The condensate line links the AC unit to the outdoor drain pipe. The line should always be clear of any blockage. A clogged condensate line will cause problems with the unit because it will not be able to drain condensed moisture. As more moisture condenses, it will end up freezing the coils.

To check for clogging in the condensate line, follow it to the outdoor outlet and check if water is dripping out as the AC defrosts. If no water is dripping, then there is a clog in the condensate line or drain. You need to remove the clogging to allow the water to flow out of the condensate line and drainage.

Clean the Evaporator Coil

Having already opened the front panel of the AC unit when checking for the freezing problem, you now need to check the evaporator coil and clean it if necessary. As the ice melts, it may reveal a dirty evaporator coil. The evaporator coil and chambers may also have mold and rust, which would create blockages. Repeated freezing and defrosting may be the cause of rusting in new evaporator chambers and coils. A buildup of rust may also be indicative of refrigerant leakage.

After the AC unit defrosts and dries, you may need to clean the dirty evaporator coil. It may also be necessary to contact a certified HVAC technician in case of damaged or malfunctioning AC parts. Integrity Heating & Cooling has a team of qualified and certified professional technicians that you can rely on to help you with the maintenance of your AC unit.

Fixing Refrigerant Leakage

Low refrigerant is a common cause of freezing in AC units. However, fixing this problem requires technical knowledge and should be done by a certified HVAC technician. In case you suspect that the freezing problem is due to refrigerant leakage, contact a qualified technician from Integrity Heating & Cooling.

At Integrity Heating & Cooling, we are proud to have a team of highly qualified and experienced technicians to serve your HVAC unit needs in Charlotte and the surrounding area. Our technicians are NATE certified, and we are an authorized Lennox and Trane dealer. Whether you need AC or heating repairs, installation, or maintenance, our team can help. We even offer emergency repairs and installation financing on approved credit. Our other services include ductwork cleaning and sealing and standby generators. Contact us today to set up an appointment or learn more about our services.