What are the access ports on the filter drier used for?

• A. Connect Gauge To System
• B. Inject Nitrogen
• C. Measure Pressure Drop Across The Filter Drier
• D. Relieve Pressure

Answer: (C)

Access ports on a filter drier are diagnostic connections that let you attach a gauge set to measure pressure on each side of the drier. By reading the inlet and outlet pressures, you can determine the pressure drop across the drier and tell whether it’s restricting flow or clogged. This helps you decide if the drier is still serviceable. They’re Schrader-type service valves designed for testing and charging access during service. They aren’t intended for injecting nitrogen or for venting/relieving system pressure; those functions use other equipment and proper procedures.