Wash Diverter; Water Temperature Sensor - Viking FDB451 Service Manual

To avoid risk of electrical shock, personal injury, or death, disconnect electrical power source to unit, unless test
procedures require power to be connected. Discharge capacitor through a resistor before attempting to service.
Ensure all ground wires are connected before certifying unit as repaired and/or operational.
(Some measurements require power and others require the unit not to be powered.)

Wash Diverter

The dishwasher uses a wash diverter to
divert water to either the upper arm or lower
arm during the wash cycle. This allows for
low water consumption and a better wash to
both upper and lower racks.
At the beginning of each wash cycle, the
control board positions the wash diverter to
its proper starting position. It is monitored by
a built in monitoring switch that sends 120
VAC back to P6-5. Depending on how long
the switch is closed determines what position
it is in.
To check the wash diverter, check the
motor with an ohmmeter between P6-2 and
Neutral. It should read approximately 2.7k Ω
ohms. If readings are incorrect, verify wiring
connections to the diverter. If the wiring is
proper, replace the wash diverter (see Wash
Diverter Disassembly procedure, page 28).
Note: If the diverter does not position itself,
a Diverter time out error will display (see Fail
Codes, page 12).
P-6
P-10
©2012 Viking Preferred Service
! WARNING

Water Temperature Sensor

The dishwasher uses a water temperature
sensor that is mounted in the sump of
the dishwasher. It is an N.T.C (Negative
Temperature Coefficient). As the temp of the
water rises, the resistance drops (and vice-
versa).
In the 200 Series dishwasher, it also
serves as a water input sensor as well.
During a fill cycle, an increase or decrease
in water temperature is monitored by the
control board. This temperate change due
to incoming water temperature fluctuations
is realized by the board as water entering
the machine. If no change in temperature is
recorded, a FILL error code will be displayed.
If the senor is open, an OPEN fail code will
signal (Refer to page 12 for fail codes).
The control board monitors P8-3 – P8-4.
Resistance should be 47K Ω @ 77˚. If no
resistance is found, check wiring. If wiring is
OK, replacement of the sensor is necessary.
P-6
P-10
Troubleshooting
P-8
P-8
39