초록 ▼

Compressor discharge temperature, ambient outdoor air temperature and thermal load are used as control parameters for controlling the expansion valve setting and indoor fan speed. Diagnostics monitor a feedback signal from the fan motor to detect fan over-speed and increased speed due to decreased a

Compressor discharge temperature, ambient outdoor air temperature and thermal load are used as control parameters for controlling the expansion valve setting and indoor fan speed. Diagnostics monitor a feedback signal from the fan motor to detect fan over-speed and increased speed due to decreased air flow caused by a dirty indoor air filter. Discharge pressure of the compressor is monitored to detect a blocked outdoor fan. The difference between actual and optimum compressor discharge temperatures and suction pressure of the compressor are monitored to detect a stuck-closed expansion valve or low refrigerant charge. Compressor “short-cycling”is limited to prevent reduced reliability of the compressor. The difference between compressor discharge temperature and outdoor coil temperature is measured before and after startup to detect compressor failure.

대표청구항 ▼

A controller for a heat pump which operates in heating and cooling modes and is of the type having a compressor for discharging refrigerant through an expansion valve (EXV) into a heat exchanger, comprising: a low pressure cutout means coupled to said compressor for electrically disconnecting said c

A controller for a heat pump which operates in heating and cooling modes and is of the type having a compressor for discharging refrigerant through an expansion valve (EXV) into a heat exchanger, comprising: a low pressure cutout means coupled to said compressor for electrically disconnecting said compressor when pressure on an inlet side of said compressor falls below a first parameter and for electrically reconnecting said compressor when said pressure rises above a second parameter; and at least one control processor, coupled to said low pressure cutout means and said EXV, for providing a low pressure malfunction diagnostic that includes: (a) a valve releasing system for attempting to free said EXV, (b) a default setting system for operating said heat pump at default settings, and (c) a counter incrementing system for incrementing a cycle counter, wherein if said cycle counter is less than a first predetermined number and said low pressure cutout means disconnects said compressor, said at least one control processor executes systems (a)-(c), and if said cycle counter equals said first predetermined number, said at least one control processor declares a malfunction.