Accumulator HVAC: Description and Operation
Suction Accumulator/DrierThe suction accumulator / drier is a canister that receives the output of low-pressure vapor from the A/C evaporator core.
The heavier, incoming oil-laden vapor settles to the bottom of the canister from which it feeds, at a controlled rate, into the compressor suction line through a bleed hole and filter. The refrigerant and oil mixture, upon entering the compressor suction line, further vaporizes, thereby preventing A/C compressor damage by eliminating the potential for refrigerant slugging.
Suction Accumulator/Drier Replacement Guidelines
Replacement of the suction accumulator/drier is necessary any time a major component of the refrigerant system is replaced. A major component includes A/C condenser core, A/C compressor, A/C evaporator core or a refrigerant hose/line. An A/C evaporator core orifice or 0-ring seal is not considered a major component but the A/C evaporator core orifice should be replaced whenever the A/C compressor is replaced for lack of performance.
In addition to the preceding condition, the suction accumulator/drier should also be replaced if one of the following conditions exist:
^ The suction accumulator/drier is perforated.
^ The refrigerant system has been opened to the atmosphere for a period of time longer than required to make a minor repair.
^ There is evidence of moisture in the system such as internal corrosion of metal refrigerant lines or the refrigerant oil is thick and dark.
NOTE: The compressor oil from vehicles equipped with an FS-10 A/C compressor may have a dark color while maintaining a normal oil viscosity. This is normal for this A/C compressor because carbon from the piston rings will discolor the oil.
When replacing the suction accumulator/drier, the procedure given here must be followed to ensure that the total oil charge in the system is correct after the new suction accumulator/drier is installed.
1. Drain the oil from the removed suction accumulator/drier into a suitable measuring container. Drill one or two 12.7mm (1/2-inch) holes in the bottom of the old suction accumulator/drier to ensure that all the oil has drained out.
2. Add the same amount of clean new refrigerant oil plus two fluid ounces to the new suction accumulator/drier. Use only the oil specified for the specific vehicle being serviced (Motorcraft YN-12b or an equivalent oil containing the same additives).