If you have recently turned on your air conditioner for the season, then you may be surprised to see that the unit appears to have ice on it after just a few days or weeks of use. Well, a frozen evaporator coil on the inside of the home is a common issue that may have several different causes. Keep reading to learn about a few and also how you can fix the problem.

Poor Air Flow

If you notice very little air coming out of your vents or if air flow has dropped significantly since you turned your AC unit on, then this is a sign that your unit is not receiving a constant flow of air through the system. This is one of the reasons why the evaporator coil may develop a layer of ice. If air does not flow past the evaporator coil, then the coil will remain quite cold. Instead of cooling air that moves past, it will cool the condensation that develops on the copper tubing instead. Ice then develops. 

Place your hand over your air vents to see if air flow is slow and stagnant. If so, then change the air filter immediately. Some dust, pollen, and other debris can gather in the air intake part of the system over the winter, and much of the debris can be forced up through the plenum and into your air filter. This means the filter can clog soon after you initially turn the AC system on.

If the filter is clean or if you have already changed it recently, then there is a chance that the blower in the evaporator is no longer working. Ask a friend to help you check the blower. First, remove the outside cover from the AC unit. Look for a large circular and metal part of the system towards the bottom or middle part of the unit. This will be the blower housing, and you can see the blower fan in the center of the housing. Ask your friend to change the temperature on one of your thermostats to activate the cooling system. Watch to see if the fan moves in the center of the blower housing. If it does not, then the blower is broken and in need of repair. 

A blocked intake vent can also cause poor air flow through the cooling system, so check the opening to see if there is any debris inside. 

Low Refrigerant

Sometimes an air conditioner can leak coolant. Most leaks are smaller ones that release refrigerant over time, and you are likely to notice a problem once the unit has retained a leak for several weeks or months. While the poor function of the machine is one sure sign of a coolant leak, so is the freezing of the evaporator coil.

When refrigerant leaks out of the system, coolant levels can vary significantly in regard to pressure. When this happens, coolant may not compress like it should and the indoor evaporator may contain both warm and supercooled refrigerant. When condensation forms on the supercooled sections of the evaporator coil, the moisture begins to freeze, and the ice can spread over the other sections of the coolant coil. 

The refrigerant must remain at a consistent PSI, and this pressure should be outlined in your AC system manual. You can look at the PSI in the manual and check the pressure gauge inside the control panel of the central AC unit. The gauge is typically located outside and connected to your compressor unit.

If you do not have a pressure gauge, then contact the best heating and air conditioning professionals to test the pressure for you. They can also recharge the system and look for leaks. The leak detection and recharging should be completed as soon as possible. If the AC system runs for too long with low refrigerant, the compressor pump may overheat and burn out.