Defrost And Moisture Control - Whirlpool WRF954CIHV Service Manual

DIAGNOSTICS
Operation
The defrost system is designed to remove ice build-up from the
Refrigerator Compartment (RC) and Freezer Compartment (FC)
evaporators when required. FC defrost is accomplished using
a heater, while RC defrost is accomplished using the relatively
warm air of the RC. The moisture control system uses heaters to
warm areas susceptible to condensation.
Freezer Compartment Defrost
The FC Evaporator is defrosted as necessary to remove frost
or ice buildup. Defrost is accomplished with a 115 VAC, 470 W
heater.
An Adaptive Defrost Control (ADC) routine determines when a
defrost cycle is needed. ADC monitors Compressor operation,
and the number of times the FC door is opened are the primary
inputs to the ADC routine.
Normal Operation
During defrost, 115 VAC power is applied to the heater from
GF2 board P2-7. The FC Evaporator Thermistor monitors the
temperature during defrost. When the FC Evaporator Thermistor
reads 50°F (10°C), defrost is ended by removing the 115 VAC
power from GF2 board P2-7.
Backup Operation
There are two thermal fuses wired in series with the defrost
heater. The thermal fuses are designed to interrupt the defrost
cycle if the normal method does not function properly. The
thermal fuses open at 183°F (84°C), interrupting power to the
heater.
Refrigerator Compartment Defrost
The RC Evaporator is defrosted at the end of each RC cooling
cycle. The RC Evaporator Fan runs for a period of time after the
completion of RC cooling. This defrosts the evaporator using the
relatively warmer air of the RC.
The fan runs until the temperature differential between the RC
Evaporator Thermistor and the RC Air Thermistor is less than
1°F (-17°C). The fan will run for a maximum of 10 minutes, after
which it shuts off, regardless of the temperature differential
between the thermistors.
Refrigerator Compartment Defrost 2018 models
The RC Evaporator is defrosted as necessary to remove frost
or ice buildup. Defrost is accomplished with a 115 VAC, 470 W
heater. An Adaptive Defrost Control (ADC) routine determines
when a defrost cycle is needed. ADC monitors Compressor
operation, and the number of times the FC door is opened are
the primary inputs to the ADC routine.
Normal Operation
During defrost, 115 VAC power is applied to the heater from
GF2 board P2-5. The FC Evaporator Thermistor monitors the
temperature during defrost. When the RC Evaporator Thermistor
reads 50°F (10°C), defrost is ended by removing the 115 VAC
power from GF2 board P2-5.
Backup Operation
There is one thermal fuses wired in series with the defrost
heater. The thermal fuse are designed to interrupt the defrost
cycle if the normal method does not function properly. The
thermal fuses open at 183°F (84°C), interrupting power to the
heater.
French-Door Bottom Mount Refrigerator
n
1-18
For Service Technician Use Only

Defrost and Moisture Control

Voltage
Heater Voltage
GF2 board
Filter 115 VAC
GF2 board
IB Duct
115 VAC
(Cabinet)
Dispenser UI
Dispenser 12.7 VDC
Dispenser UI
IB Duct
12.7 VDC
(Door)
Mullion 14 VDC
Moisture Control
The refrigerator has heaters in necessary locations to prevent
condensation. The heaters can be operated in one of two
activation modes. The default mode is for the heaters to cycle in
response to measured humidity. Humidity is measured by a
sensor located on the Main control.
Watts Resistance
Source
3
P2-6
5.5
P2-6
1.5
J8-1
1.5
J8-1
Door UI
11.5
J2-3
4800
2375
108
108
17