A filter drier is a small canister installed in the refrigerant line to remove moisture and contaminants from the system. While many of our Ductless Mini Splits have internal strainers, traditional Central Condensers often require an external drier. It acts as a final safeguard for the Inverter Compressor. If a system is opened for repair, the filter drier should always be replaced to ensure the new refrigerant stays clean. We carry various Replacement Parts to help you keep your system running smoothly. It is a critical component for preventing acid buildup and mechanical wear. You can find more information on the importance of a clean system in our Help section. This small part provides big protection for your HVAC investment.