Refrigerant monitoring apparatus and method

Apparatus for detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:

• a charge sensor positioned adjacent to the outlet of the evaporator;
• and
• a controller electrically connected to said sensor to provide an input signal thereto;
• said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor;
• said sensor producing a voltage output signal in response to said input signal;
• and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.

A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:

• positioning a charge sensor adjacent to the outlet of the evaporator;
• electrically connecting said sensor to a controller;
• sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal, including applying an at least substantially constant voltage to a voltage divider circuit to drive said sensor;
• sending said output signal from said sensor to said controller;
• in said controller, comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.

An air conditioning system comprising:

• a refrigerant circulation circuit including an evaporator with an outlet, a compressor downstream of said outlet, a condenser downstream of the compressor, and an expansion device between the condenser and the evaporator;
• and
• apparatus for detecting a reduced refrigerant charge in said circuit, said apparatus including:
• a charge sensor positioned adjacent to said outlet of the evaporator;
• and
• a controller electrically connected to said sensor to provide an input signal thereto;
• said controller applying, as said input signal, an at least substantially constant voltage to a voltage divider circuit to drive said sensor;
• said sensor producing a voltage output signal in response to said input signal;
• and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge.

Apparatus for monitoring a refrigerant state in a refrigeration system having an evaporator with an outlet, comprising:

• a charge sensor positioned adjacent to the outlet of the evaporator;
• and
• a controller electrically connected to said sensor to provide an input signal thereto;
• said sensor producing a voltage output signal in response to said input signal;
• and said controller receiving said output signal, processing said output signal, and comparing said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state;
• wherein said controller compares said output signal to said set point at preset intervals, stores a history of the resulting comparisons for a predetermined time duration, and determines a refrigerant state on the basis of said history.

A method of detecting a reduced refrigerant charge in a refrigeration system having an evaporator with an outlet, comprising:

• positioning a charge sensor adjacent to the outlet of the evaporator;
• electrically connecting said sensor to a controller;
• sending an input signal from said controller to said sensor to cause said sensor to produce a voltage output signal;
• sending said output signal from said sensor to said controller;
• in said controller, comparing at preset intervals said output signal to a predetermined set point chosen to correspond to a predetermined refrigerant state indicative of a reduced refrigerant charge, storing a history of comparisons for a predetermined time duration, and making a determination of a refrigerant charge level based on said history.