What Causes the evaporator coil (in-door coil) on an Air Conditioning system to FREEZE?

There are many ways to freeze an evaporator coil. Listed below are the most common causes. The problem can also be a combination of them.

Low Air FLOW from DIRTY air Filters and/or DIRTY Coil due to NO AIR FILTER

Reduced air flow is the MOST likely cause for coil freezing. Check the air filter and replace if necessary. The filter should be located before the fan. If no filter is installed then the fan and the evaporator coil will clog with dirt. The equipment will have to be cleaned & then proper filters installed.

Low Refrigerant Charge

The pressure of the evaporator determines what the temperature of the evaporator will be. When properly charged the evaporator should be 36 - 38 Fahrenheit. If the pressure drops slightly, the temperature will drop. When the coil reaches 32 Fahrenheit it will begin to freeze.

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