The RM assembly consists of a scroll compressor, cupronickel condenser, and service/base valves, all mounted on a newly designed condensate drain pan. Custom designed components that protect the compressor when operating at full and partial loads include: high and low pressure switches, large capacity receiver and accumulator, hot gas bypass valve, and a thermal expansion de-superheat valve. The bypass valve senses low suction pressure when cooling units are shut off, and allows refrigerant to bypass back into the compressor. The de-superheat valve evaporates refrigerant into the compressor when superheat is too high. An electrical control and relay box is mounted on the chassis, but can be remote mounted on a 3 ft. (0.9 m) harness for easy access. It includes control triggers, time delay, power delay, and start and run capacitors with a solid state relay for single-phase units, or a contactor for three -phase compressors. It is designed to be installed in the engine room or other mechanical space, and is not adversely affected by moisture, vibration, or ambient temperatures up to 140°F (60°C). Ventilation is not required.