Apparatus and methods for controlling an electronic expansion valve in a refrigerant circuit

A method of controlling a refrigerant-based air conditioning circuit having a compressor, a condenser coil, an electronic expansion valve and an evaporator coil fluid coupled in series, said method comprising the steps of:

• providing an expansion valve control;
• transmitting to said expansion valve control only signal information relating to operation of said compressor and operation of one of said condenser coil and said evaporator coil;
• and
• controlling said electronic expansion valve by transmitting from said expansion valve control to said electronic expansion valve a control signal related in a predetermined manner to said signal information.

An air conditioning system comprising:

• a refrigerant-based air conditioning circuit having a compressor, a condenser coil, an electronic expansion valve and an evaporator coil fluid coupled in series;
• and
• an expansion valve control system comprising:
• a unit control operative to receive compressor operation-related signal information and responsively generate at least one output signal representative of the received compressor operation-related signal information;
• and
• an expansion valve control operative to receive from said unit control only said at least one output signal, and to receive from one of said coils coil operation-related signal information, and to responsively output a control signal useable to control said expansion valve, said control signal being related in a predetermined manner to the signals received by said expansion valve control.