The 2 most common part(s) or condition(s) which cause the symptom Air conditioner coils freezing are listed below starting with the most likely. Check or test each item and watch any available videos.
If the air conditioner coils are freezing the cause might be a dirty air filter. As the air filter gets dirty it restricts airflow over the evaporator coils. A reduced airflow will cause the evaporator coils to get too cold, which will then cause the humidity in the room to condense on the coils and freeze. As the coils start to freeze the problem gets worse because the frost also reduces the airflow. Eventually, the entire evaporator coil assembly will frost over and there won't be any cool air.
If the air conditioner coils are freezing in only one area, there may be a sealed system leak - or refrigerant leak. This is normally a very expensive repair. If the air conditioner was inexpensive to begin with, this repair will be too costly. If this is a very expensive unit a repair may be worthwhile. This repair must be done by a qualified, licensed technician. If the entire coil is froze up the coil itself may be plugged up or the blower wheel may dirty and not drawing enough air thru the coil to melt the ice.