HVAC Maintenance: What to do when your coil freezes?

Evaporator Coil HVAC Maintenance

When summertime arrives and the cooling season begins, air conditioning (AC) problems increase. Components that comprise the AC system that has been dormant during the heating season are abruptly put into service and why HVAC Maintenance is very important.

If latent problems exist, the jolt of being suddenly put into service will draw those problems to the surface. A very common problem that leads to homeowner distress is a frozen evaporator coil.

What is the evaporator coil?

The evaporator coil is an air conditioning component located on the indoor unit associated with the furnace. You will find copper tubing connecting the furnace/evaporator coil to the outdoor compressor unit. Gaseous refrigerant moves back and forth between these two components.

The compressed gas expands in the evaporator coils and quickly cools. The cool air inside the chamber gives up the moisture it contains and cools dry air is distributed throughout the house by a blower. In turn, the gas heats up and the hot gas circulates to the outdoor compressor and gives up the heat it carries.

Why do evaporator coils freeze?

If the evaporator coil freezes, the refrigerant gas can no longer exchange heat and cold. The AC will stop cooling, even though there is a buildup of frozen water inside of the AC component. Several things can cause ice to form on the evaporator coils.

• It might be simple, like a severely clogged filter. If the filter prevents air movement, the water that is drawn out of the moist air freezes on the coil. Replacing the filter might solve the problem.
• A more common problem is low refrigerant level, usually caused by a leak. When reduced amounts of refrigerant gas are compressed, the gas cannot extract adequate heat. The gas becomes too cold and freezes the water as it evaporates. Water continues to freeze until a block of ice is formed.

If the AC fails to cool and you open the unit and discover the ice buildup, it will require a repair visit from your HVAC professional. While the coil is frozen in a block of ice, the technician can neither diagnose the problem nor fix it. We recommend that you, the homeowner, thaw the ice on the coils before the technician arrives.

How to thaw the frozen coil?

The AC will remove between 5 and 20 gallons of water from the average home. By the time you find the ice buildup on the coils, a significant amount of water will have frozen. Great care must be taken as the ice thaws—these are the procedures we recommend taking before you call a professional.

1. Turn the thermostat setting off.
2. Set the blower or Fan setting to on.
3. Place old towels at the base of the furnace unit to absorb the water as it melts. Change the towels as needed. The amount of frozen water will surprise you, so be prepared to mop as needed.
4. Monitor the thawing and be prepared for your HVAC professional as soon as possible. Thawing might take 24 hours.

The sudden loss of AC cooling followed by finding the evaporator coil frozen in a block of ice is quite distressing. Armed with the information above you can take action to remedy the situation. Then give Northwind AC a call and allow us to put your AC system back in working order.

Have Questions About Evaporator Coil HVAC Maintenance?

Northwind Air Conditioning and Heat can help with regularly scheduled HVAC maintenance and evaporator coil issues. Contact us and get the answers you need.