Accumulator HVAC: Description and Operation

Connected to the evaporator outlet pipe, the sealed accumulator assembly functions as a liquid/vapor separator. It receives refrigerant vapor, along with some liquid refrigerant and refrigerant oil from the evaporator. It allows only refrigerant vapor and oil to pass on to the compressor.

At the bottom of the accumulator is the desiccant bag. It acts as a drying agent for moisture that may have entered the system. An oil bleed hole is located near the bottom of the accumulator outlet pipe to provide an oil return path to the compressor.

A low-side pressure Schrader-type valve service fitting is located near the top of the accumulator. A similar Schrader-type fitting is provided to mount the pressure cycling switch. The system does not need to be discharged before replacing the switch. The accumulator is serviced only as a replacement assembly.

If the system is open to air for an extended period of time (due to a front-end collision, removed parts, etc.) replace the accumulator. The desiccant bag will be saturated with moisture.