What to Do If Your Evaporator Coil FreezesFrozen coils are more than a headache. In a worst case scenario, they can turn your air conditioner into a block of ice ‒ possibly burning out your fan and AC compressor in the process. If left unchecked, frozen coils can even lead to mold and water damage. Thankfully, the solution is normally simple and inexpensive. For homeowners dealing with ice inside their air conditioner, here is what to do if your evaporator coil freezes.

Why Do Evaporator Coils Freeze?

Air conditioners cool your home by circulating refrigerant between the evaporator, which absorbs heat, and the condenser, which disperses it. Refrigerant vaporizes as it enters the evaporator, lowering its temperature below 32°F so it can absorb heat rapidly from the surrounding air.

At the same time, cooling the air inside the evaporator lowers its dew point, which causes water vapor to condense and stick to the surface of the coils, like water forming on a cold glass. When the evaporator is functioning normally, the constant flow of air keeps the surface temperature of the evaporator coils around 40°F ‒ enough to cool the air without freezing moisture before it can be drained through the condensate line.

However, in order to remain stable, evaporator coils need a constant supply of warm air, otherwise their temperature drops steadily until the water on the coils turns to ice. As ice accumulates, it can create a feedback loop where icy buildup restricts air flow, which creates more ice, which restricts airflow even further.

Dangers of Frozen Coils

A frozen evaporator is more than an inconvenience. It can significantly damage your air conditioner and shorten its lifespan. Some of the most common problems homeowners encounter as a result of icy coils:

  • Warm Air. Ice insulates your coils, reducing the amount of cool air circulating through your home. While ice absorbs heat, it doesn’t absorb it as effectively as your refrigerant, which is why warm air is one of the first signs your evaporator coils have begun to freeze.
  • Rising Electricity Bills. Frozen coils slow but don’t stop the cooling process, at least not at first. In the early stages, the layer of ice forces your air conditioner to run longer during each cooling cycle, resulting in higher utility costs.
  • Greater Wear and Tear. Longer cooling cycles increase the strain on the mechanical components inside your air conditioner, especially your compressor and blower fan.
  • Frozen Condenser Coils. If the refrigerant is prevented from absorbing heat while it’s moving through the evaporator, it will still be freezing when it reaches the condenser outside. Without any heat to disperse, it’s not uncommon for the condenser coils to freeze as well.
  • System Failure. In some cases, the icy buildup becomes so extreme that the entire evaporator freezes over. At this point, airflow is completely blocked and the system can no longer function. Trying to run the system in this state may cause the compressor or fan motor to burn out.

What to Do If Your Evaporator Coils Freeze

Though frozen evaporator coils can lead to a lot of problems, most of the time, the solution is simple. First, defrost the unit by going to your thermostat and shutting down your air conditioner. You can accelerate the process by switching the unit into fan mode and circulating warm air through the system.

As the ice melts, most of the water should drain out through the condensate line. However, it’s a good idea to spread some towels around the evaporator just in case. The drain is designed to deal with small amounts of water and might overflow if you have a large amount of ice built up inside (This is the reason why frozen coils can cause water damage and increase your risk of mold. Coils freeze during the day and melt at night, forming puddles in your basement or attic).

Once the ice has melted, don’t wipe down the coils; they’re too delicate. Let them air dry while you investigate the source of the problem. In most cases, either the filter or the blower fan is responsible. Clogged filters prevent air from flowing through your system. They should be changed every 3-6 months. Replacing a filter does not require any professional help. You can purchase one from your local hardware store or order one online. Simply swap out the old one and turn the AC back on.

Blower fans are more complicated. If your air conditioner hasn’t been serviced in a while, it may be clogged with dirt as well. In which case, dusting the blades and housing should solve the problem. If the fan is clean but still doesn’t run when you restart your air conditioning, the motor is probably malfunctioning. Unless you have experience working with HVAC equipment, the best advice is to call a professional.

What to Do If the Problem Reoccurs

Though poor airflow is the primary cause of frozen coils, it’s not the only one. If the problem persists even after cleaning the fan and replacing the filter, you may be dealing with a refrigerant leak. When refrigerant levels fall, the system’s ability to absorb heat falls as well. Refrigerant levels are carefully calibrated during installation, so even a small loss of pressure can cause surface temperatures to dip below freezing inside the evaporator.

Refrigerant lines are made of copper and encased inside the condenser, evaporator, and walls of your home, where they’re shielded from the elements. As such, leaks are relatively rare, which is why the signs often go unnoticed. Homeowners who have checked the airflow through their system are often annoyed when they find their coils repeatedly freezing over. If you notice the same thing happening in your home, call an HVAC technician right away. They’ll measure your refrigerant levels and, if there’s a leak, track it down and seal it.

Save on Air Conditioner Repairs with Agway EnergyGuardTM

Evaporator coils are one of the most important parts of your air conditioning system ‒ responsible for managing temperatures inside your home. Replacing your coils can be costly, so make sure they’re protected. Agway’s EnergyGuardTM Program covers your heating, cooling, and electrical systems against wear and tear. Home insurance doesn’t cover this type of damage, but we do.

When the need for repair occurs, our customers don’t have to hunt around for a qualified technician. We maintain an extensive network of contractors and will send the first available one straight to your door. There’s no need to worry about service fees or deductibles either. We pay for the visit and all covered parts. Sign up and start enjoying the benefits of EnergyGuardTM today!