Driers perform a few different functions on the A/C system. First of all, they are a storage tank for excess refrigerant. Under certain operating conditions where heat loads are reduced, the evaporator does not require the same amount of refrigerant as when heat loads are extremely high. In those cases, the liquid line receiver drier will hold excess refrigerant.

The drier will also trap moisture in the system. Using a drying agent like silica gel desiccant, the drier forces the flow of all refrigerant through the filter section in order to be drier. That filter section also includes other filter media that will trap and hold debris and other contamination that may be in the system.

Order list of off the shelf parts bought directly by the customer to save on the cost of conversion. It is contained in the pre-install support section.