The purpose of desiccant in the refrigerant filter dryer is to

• A. Remove moisture
• B. Hold moisture
• C. Absorb moisture
• D. Lubricate seals

Answer: (B)

Moisture in the refrigerant can cause ice in the expansion path, accelerate acid formation, and promote corrosion of metal parts and oil degradation. The desiccant in the filter dryer is there to attract water vapor from the circulating refrigerant and hold it in its porous structure. By capturing and keeping that moisture inside the desiccant, the refrigerant stays dry enough to protect the system downstream. It’s not there to lubricate seals; its purpose is to trap moisture so it doesn’t circulate with the refrigerant, and the desiccant must be replaced when it becomes saturated.