Amana Bottom Mount Refrigerator Freezer Compartment Refrigeration Cycle Circuitry

Electronic Functional Description

Circuitry

Refer to “Technical Data Sheet”, part #12074201, for Wiring Schematic.

Freezer Compartment Refrigeration Cycle Circuitry

As freezer thermistor warms, resistance lessons, allowing low voltage signal to be sent to electronic control. In turn, 2 low voltage signals are sent by electronic control. One to compressor relay coil (C1) and another to evaporator fan relay coil (F1). With both relay coils energized and contacts closed, high voltage circuits to compressor, condenser fan motor, and evaporator fan motor are complete.

As thermistor cools during refrigeration cycle, resistance through thermistor increases, blocking low voltage signal to electronic control, interrupting the cycle.

Fresh Food Compartment Refrigeration Cycle Circuitry

As fresh food thermistor warms, resistance lessens, allowing low voltage signal to be sent to electronic control. In turn, electronic control sends low voltage signal to 24 VDC fresh food fan.

When fresh food fan motor operates, freezer air is circulated into fresh food compartment. As fresh food thermistor cools, resistance increases, blocking low voltage signal to electronic control. In turn, electronic control interrupts the signal to fresh food fan motor.

Fresh Food and Freezer Compartment Refrigeration Cycle Circuitry

Many times cooling will be called for in both compartments as both freezer and fresh food thermistors warm. Resulting is electronic control signaling for compressor, condenser fan motor, evaporator fan motor, and 24 VDC fresh food fan to operate. Once freezer thermistor has been cooled sufficiently to block the signal to electronic control, the compressor, condenser fan motor, and evaporator fan motor will shut down. However, fresh food fan motor will continue to function until fresh food thermistor cools and blocks the signal to electronic control.

If fresh food thermistor is cooled prior to freezer thermistor, the electronic control will interrupt the signal to the fresh food fan motor. The compressor, condenser fan motor, and evaporator fan motor will remain in operation through freezer thermistor.

Adaptive Defrost Circuitry

After proper compressor run time (either 8, 12, or 16 hours), refrigeration cycle is interrupted and a low voltage signal is sent form electronic control to defrost relay coil (D1 DEF). Powering of relay coil closes relay contact (D1), completing the high voltage circuit to the defrost heater through the closed defrost terminator (closes at 20°F (-7°C)). The isolator, part of high voltage PC board, recognizes the presence of line voltage to the defrost heater. Isolator sends a low voltage signal to electronic control which keeps count of the number of minutes defrost terminator remains closed (opens at 55°F (13°C)). Length of time defrost terminator remains closed, determines whether next defrost cycle advances by 4 hours of compressor run, stays at same interval or backs up by 4 hours of compressor run. If defrost terminator does not open before 30 minutes, defrost cycle will automatically be terminated by electronic control and refrigeration cycle will resume after a 6 minute dwell time.

Important: When Showroom switch is off, isolator see's line voltage. In turn, isolator keeps electronic controller from signaling compressor, condenser fan motor, and evaporator fan motor relay coils and keeps fresh food fan motor off.

November 1996 33 RS1200001