Patent ID: 8454229

Claim:
A method for sensing a fluid in a compressor, wherein the fluid can exist in a plurality of states including at least one of a liquid state, a gaseous state, and a gas/liquid mixture, the method comprising: positioning a thermistor in heat transfer relationship with the fluid; electrically heating the thermistor to a heated temperature that is higher than a fluid temperature of the fluid; after electrically heating the thermistor, allowing the thermistor to cool toward the fluid temperature, wherein the thermistor cools at a cooling rate; as the thermistor cools, determining the cooling rate by repeatedly sampling a temperature of the thermistor over a sample period; determining in which state the fluid exists based on the cooling rate; and determining the fluid temperature based on the cooling rate, wherein the fluid temperature is determined prior to the thermistor actually reaching the fluid temperature and the step of determining the fluid temperature is accomplished independent of any calculated time constant, exponential function, and exponential look up table.