Should My Air Conditioner Be Freezing Up?


The weather is warming up, and you have started using the air conditioning for the season. You have noticed it has started to freeze up, and it is not working as well as it did last year. This may leave you to wonder: Should your system be freezing, what causes it to do so, and what can you do about it?

Understanding Air Conditioning Functions

Before jumping into the causes of air conditioning freezes, it may be prudent to understand some basics of your system. To cool your air, your AC unit draws air from your home into your air conditioner. It absorbs the heat from that air with the refrigerant and then pushes it outside to vent that heat.

In order to work, your system needs to regulate the pressure of the refrigerant. As the refrigerant pressure drops, it becomes extremely cold, allowing it to better absorb heat. However, if you increase the pressure, your air conditioner condenses the heat that it contains, allowing it to transfer to the heat outside.

In addition to regulating refrigerant, your system must have air flowing through it. If either of these are interrupted, it will not work as intended to cool your house.

Restricted Airflow

Airflow restrictions are some of the most common issues with air conditioners, leading to reduced airflow and ineffective cooling. These restrictions could be from a clogged air filter, a dirty evaporator coil, or a circulating fan.

The air filter captures most of the airborne contaminants before they have a chance to enter your unit. To keep the air flowing well, you should plan to replace your air filter regularly, about every 90 days. Consider checking your filters monthly, and gently vacuum off the intake side to help extend their service lives.

As your system runs, some contaminants will make it past your air filter and settle in your unit. One place they settle is on the circulating fan, which is responsible for moving all the air through your AC unit. These contaminants collect slowly, but eventually the particulates lead to less air being drawn in and pushed out.

The other place these contaminants settle is on the evaporator coil, which is where the refrigerant gets cold. As the contaminants settle on it, they restrict airflow and cause a form of insulation. The effect is less heat transferred to the refrigerant from the air circulating as well as less air circulating.

All of these situations lead to the refrigerant not absorbing the right amount of heat. This results in the refrigerant freezing downstream from the evaporator coil.

Mechanical Failure

Every mechanical device is subject to wear and tear and component failure, and air conditioners are no different. One of the primary components that can cause your system to freeze up is a failing circulating fan.

As the fan motor ages, it may not spin quickly enough to draw in the right amount of air. The result of a circulating fan failure is nearly the same as that of an airflow restriction.

Low Refrigerant Pressure

Your refrigerant level must be within a very tight tolerance to allow the system to run properly. If there is too much refrigerant, the unit cannot get cold enough at the evaporator coil to absorb heat.

Having too little refrigerant is just as problematic, preventing the air conditioner from building enough pressure. Not only does this prevent the heat from compressing enough to transfer to the outside air, but it also causes freezes.

As already mentioned, refrigerant gets cold when the pressure drops. Even with too little refrigerant in the system, the compressor will still attempt to build the pressure at the condenser. This creates a situation in which the pressure drops unusually in the lines leading up to the compressor, creating frozen lines.

In addition to frozen lines, this lack of refrigerant puts a lot of strain on the compressor. Without the right amount of refrigerant in the AC unit, your compressor will burn out, leading to preventable repairs.

The Role of Routine Maintenance

Professional routine maintenance is the best protection against summer AC freezes. During a maintenance visit, a technician will clean your evaporator coil and circulating fan, resolving many airflow restrictions. They will also inspect your air filter to see if it is time to replace that as well.

They will then test each component in your system to ensure it is operating within optimal parameters. Finally, they will check the refrigerant level to ensure the right amount is within the system.

People around Arlington have turned to Texas Air Authorities for professional air conditioning maintenance since 1999. We have also been sought for our expertise in heating and cooling installation and repairs, along with our indoor air quality solutions. Call to schedule your AC maintenance appointment with one of our technicians today.

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