Accumulator HVAC: Description and Operation

Accumulator
Refrigerant leaving the evaporator flows into the accumulator, which acts as a holding tank and separates any remaining liquid refrigerant from the vapor. Refrigerant oil also collects in the accumulator. At the bottom of the accumulator is a packet of desiccant, which absorbs and holds any moisture that may have entered the refrigeration system. This desiccant is specifically designed for R-134a.

Refrigerant exits from the top of the accumulator to insure that no liquid refrigerant enters the compressor. An oil bleed hole in the outlet pipe provides a path for lubricating oil to reach the compressor.
The accumulator is serviced as an assembly by replacement, but should ONLY be replaced when the shell is perforated and a refrigerant leak is found, or if the system has been open for a prolonged period of time (greater than 24 hours).

Accumulators for R-134a systems have metric fittings identified by a grove cut into fitting flats. Replace only with like Accumulator or thread damage will result.