When the outdoor temperature is escalating, you depend on your air conditioner to perform optimally. But, machines can have system problems at some point and an AC unit can freeze up. You may say that your AC is supposed to put out cool air, so why is “freezing” not a good thing? If your AC unit is not producing cold air because it is freezing up, you are experiencing the reality that something has gone wrong and the elements of producing cool air are out of balance. Your air conditioner operates through a refined control of temperature, pressure, and airflow. When any of these things fail to work properly, you will feel less than cool air coming through your vents.
There are several possible reasons why your unit is freezing up, and you may need an AC repair. At R & S Mechanical, we are very experienced in diagnosing problems. In this article, we want to give you four common reasons why your AC unit is freezing up and what you may be able to do about these issues.
How Do You Know If Your AC Unit Is Freezing Up?
There are two obvious signs that your AC unit is freezing up. The first sign is visible ice on any part of the unit and the second sign is a lack of cool air. If you hold your hand in front of your supply vents and there is warm air coming out, then you probably have ice somewhere in the system.
Reason #1: Low Refrigerant
If your system is low on refrigerant, this can cause the unit to freeze up. Refrigerant is a liquid that cools the air before it enters your home and the AC unit requires a certain amount of it to operate properly. The level of refrigerant inside the coils matters significantly because of how the AC manages pressure. The big unit that is outside your house is compressing refrigerant after releasing the heat it collects. Warm air converts (“flashes”) liquid refrigerant into a gas that heats up and drops pressure. Then, the compressor compresses it back into a liquid and pumps it toward the blower fan inside the house.
When there isn’t enough refrigerant in the system, the pressure will drop inside the unit, which in turn causes temperatures to fall in the evaporator coils. The temperatures can sometimes dip below freezing. If this happens, the water vapor that is near adheres on the coils and freezes. The coat of frost accumulates on the coils and can eventually build up to a thick sheet of ice.
What To Do
The logical conclusion is to add more refrigerant when it is low. But, any HVAC professional will advise against this. Because an AC unit is a closed system and refrigerant doesn’t evaporate, low refrigerant levels can indicate there is a leak. A leak can occur in the refrigerant lines, compressor, or evaporator coil. If you suspect you may have a leak, and you more than likely do if you have low refrigerant levels, then call a professional HVAC technician to check.
Reason #2: Lack of Airflow
Another very common reason for your AC unit freezing up is having poor airflow. Airflow is essential for your AC unit to function properly. If air isn’t flowing as it should, the system will not work effectively. There are several reasons why your AC unit may have airflow problems.
Clogged Air Filter
A clogged air intake filter can cause the AC unit to freeze up. This filter is between your dusty home vent and the AC unit. It keeps the air and your compressor coils clean. When it fills up with dust, it becomes an obstruction rather than a clear path for air. A clogged air filter slows down airflow to a crawl and no amount of blower efficiency can keep your AC coils from freezing. Even if your AC system is functioning properly, weak airflow through your filters can lead to your home being uncomfortable. Always make sure the filters are clean.
Air Duct Issues
The air conditioning air ducts are essential for a properly working system. From leaks to blockages, air duct problems can result in very poor airflow. This, in turn, can cause coils to freeze because there isn’t enough warm air to keep them at the optimal temperature.
Faulty Blower Motor
The blower motor and fan help to blow air over the coils in the system, which helps to create cool air. When this fan ceases to work, cool air won’t come from your vents and, ultimately, causes a frozen AC unit. If the fan stops blowing, whether from the motor or the blower motor’s run capacitor, the air stops flowing quickly enough over the coils. And, when the air stops flowing, the coils start freezing. Inspect the blower motor and fan. If this is the problem, you might hear irregular or rattling sounds from the AC unit.
Low Voltage to the Fan
Sometimes the problem is with the electricity in your home. AC units require electrical power to a variety of high-power components to run. If your fan or blower motor are under-powered while the compressor continues to run, then your unit will freeze up.
Reason #3: Blockages on Coils
Dust on the AC refrigerant coils can occur from having dirty air filters. Because the coils are usually wet from surrounding moisture, dust can stick to them easily. Dust acts as an insulator, making it hard for the cold to escape the coils. This causes ice formation which accumulates and can create thick sheets of ice to form on the coils.
Reason #4: Drainage Problems
In humid climates like North Carolina, a lot of water vapor is turned into condensation within the air conditioner. When hot, humid air blows across the evaporator coil, the coil removes heat as well as moisture from the air. Under normal circumstances, the water drips into a pan and out a floor drain. If there is a blockage, the backed-up water freezes all the way back to the evaporator coil, the ice blocks the drain, and the problem gets worse. You can check and clear the drainpipe weekly during the hottest parts of the summer. A normally functioning drain will show the water dripping into the pan and exiting through the floor drain.
Contact R & S Mechanical Services in Raleigh When Your AC is Freezing Up
If your AC isn’t putting out cool air in the summer and you suspect that the AC unit is frozen, give us a call! Our experienced team provides superior heating, air conditioning, and refrigeration services in the Raleigh area and can quickly diagnose and correct your AC issues. Call the Comfort Guy of R & S Mechanical at (919) 302-8956 today or complete the form below. We are happy to assist you!
