Where is the low pressure valve for the ac on a 1998 mercury mystique 4-cylinder?

There is a low pressure switch located on the suction accumulator/drier which is located under the hood of the engine compartment. Standing in front of the engine compartment look straight down a little to your right up close to the engine radiator and see the drier. There are 2 refrigerant lines and an electrical connection on the drier, this connector is connected to the low pressure switch on the drier. Hope this helps you. Serg.............