Convection Fan; Convection Operation - Viking RDSCD230-5B Service Manual

Troubleshooting
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.

Convection Fan

Locate the P4 connector and line break relay. The P4
connector will have a Molex plug containing 4 wires:
(1) blue/black wire - FWD motor winding and
HI speed capacitor
(2) yellow/white wire - REV motor winding
(3) orange/white wire- LO speed capacitor
(4) orange/black wire - HI speed capacitor

Convection Operation

The convection system consists of a two-speed, two-
direction fan motor. The main power, speed, and
direction are controlled by the oven control board by
three relays (K5, K6, and K7). K5 is the main control
(Power) relay and is an SPDT relay. It controls all
functions of the convection fan system. The photo below
shows the K5 relay energized.
Clockwise (FWD)–Low Speed
When closed, it sends power to the common terminal of
the K6 relay (direction) and is an SPDT relay.
The output from K5 is connected to the C (common)
terminal of K6. When it is not energized (as shown
above), power flows through the C terminal, to the N.C.
(normally closed) contact and out the FWD contact on
the board.
14
K7 is the speed relay. It is an SPDT relay. When not
energized, the LO circuit is energized through C terminal
of the K7 relay. This will cause both capacitors to be
in series causing the fan to run at a reduced speed.
The photo below shows the K7 energized. The N.O.
(normally open) terminal is now closed causing a bypass
of one of the two capacitors. With only one capacitor in
series, the unit will run at a higher speed.
Clockwise (FWD)–High Speed
The photo below shows the K6 relay energized
which will cause the motor to rotate in a REV
(counterclockwise) direction. K7 is not closed, so the
speed is LOW.
Counterclockwise (REV)–Low Speed
The photo below shows the K6 (direction) and K7
(speed) relays energized. This will cause the motor to
rotate in a REV (counterclockwise) direction and at a
higher speed.
Counterclockwise (REV)–High Speed
To check the individual direction and speeds, perform
the following checks:
©2012 Viking Preferred Service