Accumulator HVAC: Description and Operation

NOTE: 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 O-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.

The suction accumulator/drier is mounted to the A/C accumulator bracket and positioned to the right of the radiator. The inlet tube of the suction accumulator/drier attaches to the A/C evaporator core. The outlet attaches to the A/C manifold and tube.

After entering the inlet of the suction accumulator/drier, heavier oil-laden refrigerant contacts an internally mounted dome, which serves as an umbrella, and drips down onto the bottom of the canister. A small diameter oil bleed hole, in the bottom of the vapor return tube, allows the accumulated heavier liquid refrigerant and oil mixture to re-enter the compressor suction line at a controlled rate. As the heavier liquid refrigerant and oil mixture passes through the small diameter liquid bleed hole, it has a second chance to vaporize and recirculate through the A/C compressor without causing damage due to slugging.

A fine mesh screened filter fits tightly around the bottom of the vapor return tube to filter out refrigerant system contaminant particles. A desiccant bag is mounted inside the canister to absorb any moisture which may be in the refrigerant system.

A fitting located on the top of the suction accumulator/drier is used to attach the A/C cycling switch. A long-travel Schrader-type valve stem core is installed in the fitting opening to prevent refrigerant loss when the A/C cycling switch is removed.

In addition to the preceding conditions, the suction accumulator/drier should also be replaced if one of the following conditions exists:
^ 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: Upon replacement of the accumulator, it is necessary to measure the quantity of refrigerant oil. To do this drill two 13 mm (1/2 inch) holes in the suction accumulator/drier body and drain oil through the holes into a calibrated measuring device.