Air Conditioner Filter Dryer for 1971-1973 Mustangs. The filter-
drier is a canister typically mounted near the condenser that
receives most of the liquid from the condenser. It has two
primary functions in the air conditioning system: 1) Filter
contaminants. This is the primary location where larger
contaminants will end up. 2) The desiccant stored inside removes
any residual moisture from the system that evacuating doesn?t
remove. This is the most important function, as moisture is the
#1 enemy of the air conditioning system. Combined with
refrigerant and lubrication, moisture will turn acidic
(hydrochloric acid) and start to eat the system up from the
inside out. It is necessary to replace or restore the filter-
drier whenever the system is opened up to the atmosphere.