Patent ID: 8393787

Claim:
A method for sensing a fluid in a compressor, wherein the fluid exists in at least one of a plurality of states including at least one of a liquid state, a gaseous state, and a gas/liquid mixture, the method comprising: cyclically electrically heating and thermally cooling a thermistor that has a temperature that varies and is in heat transfer relationship with the fluid so that the thermistor experiences a plurality of temperatures during a plurality of heating and cooling cycles, the temperature of the thermistor decreases during the cooling cycle; measuring the plurality of temperatures of the thermistor while the temperature of the thermistor decreases as a result of the temperature of the thermistor being greater than that of the fluid during the cooling cycle; calculating via a microprocessor, a delta-temperature ratio involving the plurality of temperatures that the thermistor experienced during the plurality of heating and cooling cycles; and determining, via the microprocessor, in which state the fluid exists based on magnitude of the delta-temperature ratio, wherein the magnitude of the delta-temperature ratio indicates in which of the liquid state, the gaseous state and the gas/liquid mixture that the fluid exists.