Automatic expansion valves are used on some room air conditioners instead of the capillary tubes to control the flow of refrigerant into the evaporator. These valves are set to maintain a normal suction pressure. They are factory adjusted and sealed, and no field adjustment is required. A small bleed port in the valve permits pressure equalization from the high to low side on shutdown. A small liquidline strainer is located in the liquid line ahead of the expansion valve.
