Automotive Air Conditioning Desiccant
Desiccant is the material that is used as the drying agent to remove moisture from the refrigerant and oil in your a/c system.The Receiver Drier and Accumulator contains a bag of dessicant which is used to trap system damaging moisture. Moisture inside your a/c system can cause ice formation and corrosion. Acid that forms when refrigerant mixes with moisture can weaken aluminum components such as the Condenser and Evaporator.
Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers and accumulators use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.
Because desiccant materials break down with age and the bag that contains it can rupture, you should replace the Receiver Drier or Accumulator if it's over five years old - or - any time the system is opened for major repair.
