- When should I change a filter drier?
A liquid line filter drier typically needs to be replaced when the system is opened to atmosphere.
Filter driers should be cut out of a system instead of un-soldered because the heat will release moisture form the drier being removed.
Suction line filter driers should not be replaced until the system is known to be clean and no longer has acids in the system after a compressor burnout.
Suction line filter driers with excessive pressure drop should be removed from a system. This is because an excessive pressure drop will reduce system capacity.
A good rule of thumb to determine if a filter drier needs replacement is if there is a 2 °F or 2 psig pressure drop across the filter drier.
If a filter drier is added to the liquid line of a system that previously did not have a filter drier, add additional refrigerant to the unit to fill the interior space of the drier. No charge is necessary if a drier is added to the suction line.
When servicing in the field, it is advisable to replace the original filter drier with one of the original size or the next larger size.