Relay Board Diagnosis - Viking RDSOE306SS Service Manual

Service Diagnostics and Procedures

Relay Board Diagnosis

Fan Relay
The unit is designed to operate a two-speed cooling
motor. The RDSOE and RDDOE series utilize a
one- speed motor so both the HI and LO speeds
are jumped together on the relay board. On initial
startup, the Fan Power relay (K8) and the LO speed
(K9) is selected. When the oven temp reaches
proper temperature, the board will switch the speed
relay to HI. However, both are jumped together so
this change is not noticed. If a fan error is shown,
proceed with the test shown below.
When the unit is switched on, voltage is sent to the
fan relay coil(s). A red LED (D20, D22) in front of
each coil verifies coil voltage is being sent to that
particular relay. This does not indicate however that
the relays are functioning.
When a cooking program is activated, the initial
cooling fan speed depends on the cycle selected.
When set for CONVECTION ROAST, CONVECTION
BROIL, HIGH BROIL, MEDIUM BROIL and SELF
CLEAN, the fan runs at HIGH speed.
BAKE, CONVECTION BAKE, TRU CONVECTION
and LOW BROIL start at LOW speed and when the
oven temperature reaches 400˚F, the EOC switches
to HIGH speed.
When the oven is turned off (cycle selector in OFF
position), the fan switches from high to low when
the temperature at the RTD drops below 375˚F, and
shuts off completely when the temperature drops
below 250˚F.
To test, disconnect power and disconnect P11
Molex plug. With voltmeter set for AC voltage, check
between neutral and the terminal. The reading
should be 120 VAC. If 0 volts are shown and the red
LED (D20 D22) is illuminated, the relay board should
be replaced.
© 2012 Viking Preferred Service
Fan–Hi Speed
When the EOC calls fan operation, K8 relay is
energized and the fan operates. When a program
calls for LOW speed, K9 is energized. Because both
are tied together, the results are the same.
With both relays engaged and voltmeter set
for AC voltage, check between neutral and
each terminal. The reading should be 120 VAC.
If 0 volts is measured and red LED (D20 D22)
is illuminated, then the relay board needs to be
replaced.
Fan–Lo Speed
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