A refrigeration system (10) includes a compressor (20) having a first stage (20a) and a second stage (20b); a heat rejecting heat exchanger (40) having a fan (44) drawing ambient fluid over the heat rejecting heat exchanger, the heat rejecting heat exchanger including an inter- cooler (43) and a gas cooler(41), the intercooler coupled to an outlet of the first stage and the gas cooler coupled to an outlet of the second stage; , an unload valve (93) coupled to an outlet of the intercooler and a suction port of the first stage; a flash tank (70) coupled to an outlet of the gas cooler; a primary expansion device (55) coupled to an outlet of the flash tank; a heat absorbing heat exchanger (50) coupled to an outlet of the primary expansion device, an outlet of the heat absorbing heat exchanger coupled to the suction port of the first stage; and a controller (100) for executing a startup process.