A frozen or damaged evaporator coil can grind your HVAC system to a halt.

Coils can freeze for many reasons. If air flow across the coil is restricted, the coil's temperature could drop below the freezing point, thus allowing the condensate to freeze solid. In these cases you should check the air filter to make sure it's clean, as well as the coil's intake side.

One important thing to remember when dealing with a frozen or damaged coil is to shut your HVAC system down immediately. A frozen or damaged coil can tax the compressor, thus eventually breaking the HVAC system.