Question 42Refrigeration & AC - Assistant Engineer

The correct answer is A) discharge of the compressor lube oil pump. The unloader power element piston of the refrigeration compressor capacity control mechanism is typically actuated by the discharge pressure of the compressor's lube oil pump. This pressurized oil from the pump acts against the underside of the piston, providing the necessary force to control the compressor's capacity. The other options are incorrect because: B) the gas discharge from the compressor would not be a suitable fluid source for this mechanism, C) the high-side liquid receiver does not contain the appropriate pressurized fluid, and D) a secondary hydraulic pump is not typically used for this purpose in a standard refrigeration system.