A vapor compress1on cond1t1on1ng systemuncludes a motor operated expanslon valve and control un1t 1nclud1ng
sensors for determining the amount of superheat of the at or adjacent to the compressor inlet. Expansion
valve position is adjusted to maintain a predetermined
amount of superheat. The sensors may sense Working ?uid
evaporator temperature and temperature downstream of the
evaporator. Dual motor operated expansion valves may be
disposed in the Working ?uid conduit betWeen the heat
exchangers in a reversible system. In operation, the expansion
valve position may be set as a function of ambient tempera
ture, a previous position, and predetermined superheat
requirements to minimize liquid ingestion by the compressor.