Question 2Refrigeration & AC - 1st Asst/Chief

The correct answer is B) discharge of the compressor lube oil pump. The fluid used as a source of actuating power against the underside of the unloader power element piston of the refrigeration compressor capacity control mechanism is obtained from the discharge of the compressor lube oil pump. This pump circulates lubricating oil throughout the compressor, and a portion of this pressurized oil is diverted to provide the necessary hydraulic force to actuate the unloader mechanism and control the compressor capacity. The other options are incorrect because: A) the gas discharge from the compressor would not provide the necessary hydraulic power; C) the high side liquid receiver does not contain a pressurized fluid source; and D) a secondary hydraulic pump is not typically used for this purpose in standard refrigeration compressor capacity control systems.