Icing or Frozen on Cooling Coils

Faulty Fan / Blower 

• Moisture from air is removed and generally forms condensation on the evaporator coils.
• Airflow allows the coils to stay above freezing so the condensation can run down into a pan and drain away.
• Airflow not moving the fast enough allows the condensation to remain on the coil for too long and also the warmer outside air is less effective in keeping the coils above freezing.
• The combination of the two factors leads to ice formation on the coils.

Air filters, blower or cooling coil dirty

• Similar to the airflow problem caused by a faulty fan on the evaporator potion of the system, debris can also restrict the air entering the outside unit.
• If leaves any type of debris prevent fresh air from being pulled into the chamber where the evaporator is located, the condensation may be able to freeze on the coils before draining away.
• And once the freezing process begins, it will continue. Even turning off the system and allowing it to restore cooling for a short time.
• Unless the cause of the icing is remedied, it will eventually happen again. A dirty air filter could potentially cause this same type of problem.

Low / Insufficient Refrigerant gas 

• When air conditioning refrigerant is running low, it can cause ice to form on the evaporator coil or the suction line.
• It may seem unlikely that low refrigerant causes a component of the air conditioner to ice up, but it’s true.
• When there is too little freon or other refrigerant in the system, part of the coils will be far colder than the other parts.
• This inconsistency will cause excessive condensation in one area of the coil, which then forms ice.
• As the ice forms, it makes it possible for more ice to form. It acts as an insulator and allows the coil to freeze up.