Why do air conditioner coils freeze up?

Low airflow, dramatic temperature settings or a slight undercharge of refrigerant are the most common reasons for an air conditioning coil freeze. If your air conditioner coil is freezing up start first by changing your air filter...

Low Air Flow:
Low air flow is the most common reason for coils freezing. This can result from a dirty filter, a dirty or damaged evaporator coil, or restrictions within the air ducts.

To prevent the air conditioner coil from freezing due to low air flow:

1. Change your air filter every 2 months. Do not use filters that are too restrictive to air flow. (We suggest air filters that have a MERV rating between 7 - 11)
   
2. Have the air ducts cleaned every 3-5 years to lessen the amount of debris drawn within the heating and cooling components.
   

Dramatic Temperature Settings:
Dramatic temperature settings is when the temperature on thermostat is set too low. Coil freeze from dramatic temperature settings can also occur when the air conditioner is turned off during the day while the homeowner is at work in a effort to conserve energy and turned on to a low temperature setting when the homeowner returns from work.

To prevent the air conditioner coil from freezing due to dramatic temperature changes:

1. Never lower the thermostat to under 70 degrees
2. Avoid turning the air conditioner off during the day. Set the temperature of the thermostat to a temperature 10 degrees above what it is typically set when you are away, or invest in a thermostat that automatically adjusts the temperature.
   

Undercharge of Refrigerant
Overtime gaskets and seals of air conditioning components will wear of deteriorate allowing for the loss of refrigerant.

To prevent the air conditioner coil from freezing due an undercharge of refrigerant:

1. Have the air conditioner inspected each year by an HVAC contractor to ensure for proper levels of refrigerant, and that the unit is operating efficiently.