Amana SR520T Service page 32

Electronic Functional Description
To avoid electrical shock which can cause severe personal injury or death, disconnect power to refrigerator using
power switch before servicing. Discharge capacitors through a resistor before handling. Wires removed during
disassembly must be replaced on proper terminals to insure correct earthing and polarization. After servicing,
reconnect power using power switch.
Adaptive Defrost
After designated compressor run time, refrigeration
cycle is interrupted and electronic control sends a low
voltage signal to defrost relay coil (def D1).
Powering the relay coil closed relay contact (D1)
completing high voltage circuit to defrost heater
through closed defrost terminator (closes at -9°C).
Isolator, which is part of high voltage PC board,
recognizes presence of line voltage to defrost heater
and sends low voltage signal to electronic control.
Electronic control keeps count of number of minutes
defrost terminator remains closed (opens at 9°C).
RS5290000 Rev. 0
!
WARNING
230 VAC
IMPORTANT: When the power switch is OFF , the
isolator see's line voltage which keeps the
electronic controller from signaling the
evaporator fan motor or the compressor relay
coils and also keeps the damper heater off.
Length of time defrost terminator is closed determines
if the next defrost cycle advances by 3 hours of
compressor run, stays at the same interval, or delays
by 3 hours of compressor run.
If defrost terminator does not open before 29 minutes,
defrost cycle is automatically terminated by electronic
control and refrigeration cycles will resume after 6
minute dwell time.
34 April 1998