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FULL SIZE GAS CONVECTION OVENS - ELECTRICAL OPERATION
F24682 (Rev. B, October 2007)Page 39 of 68
J. Roast timer (normal cooking) in the OFF
position.
K. Roast and Hold timer in the OFF position.
L. Oven doors Closed.
1) Door switch contacts CLOSED.
M. Oven cavity temperature below 140°F.
2. Set controlling thermostat to desired ROAST
then Hold temperature (Roast & Hold cooking).
NOTE: This is considered first stage cooking in the
ROAST & HOLD cycle.
A. Internal contacts close.
3. Power switch (S1) turned ON.
A. Power to motor speed (Hi/Low) relay (R1)
normally open (N.O.) contacts and hold
relay (R2) common (C).
B. Component cooling fan energized.
C. Power ON light (Amber) comes ON.
D. Power to one side of the following
components: Normal ROAST timer
terminal 1, ROAST & HOLD timer terminal
1, transformer primary (T1).
NOTE: Power is available to the oven light
switch (wire #20) to turn the oven cavity
lights ON when the light switch is turned
ON; and power is available to the normally
open N.O. side (wire #28) of the door
switch contacts and connects power to
additional components when the door
switch contacts are CLOSED (door
closed).
1) Transformer (T1) energized.
a. Power (24VAC) to one side of
the following components: heat
relay (R3) normally open (N.O.)
contacts, high limit—connected
through the normally closed
(N.C.) contacts to the 1
st
valve
(safety) on the dual solenoid gas
valve.
a) 1
st
valve (safety) on the gas
valve energized.
NOTE: Gas does not flow to the
burner until the 2
nd
valve (main)
is energized.
2) With door switch closed, power is
connected through a second set of
contacts on the power switch (S1),
through the thermostat contacts,
through one set of relay R4 normally
closed (N.C.) contacts, to one side of
the centrifugal switch on the
convection fan motor.
a. Heat light (clear) comes ON.
3) Power is also connected through the
another set of relay R4 normally
closed (N.C.) contacts to the other
side of motor speed relay (R1).
a. Motor speed relay (R1)
energized, contacts change state
and the normally open (N.O.) set
of contacts close.
a) Convection fan motor
energized (fan speed low).
NOTE: In the ROAST & HOLD
cycle, the fan speed is fixed at
low.
b. When the convection fan motor
reaches operating speed, the
centrifugal switch on the motor
closes. The heat relay (R3) is
then energized, R3 relay
contacts normally open (N.O.)
close and the heating circuit is
powered.
a) Ignition control module is
energized.
b) No ignition light (red) comes
ON, module performs a self
diagnostic test for 4
seconds, 2nd valve (main)
on the gas valve is
energized. Gas starts to flow
to the burner, sparking
begins, the NO IGNITION
light goes out and burner
lights. Sparking continues
for up to 7 seconds or until a
flame is established. If a
flame is SENSED, the NO
IGNITION light stays out
and burner remains lit.
If a flame is not SENSED
after 7 seconds of sparking,
the NO IGNITION light
comes back on, 2
nd
valve
(main) on the gas valve is
de-energized and gas flow
to the burner stops. Ignition
trial cycle repeats after a 15
second purge between
cycles for two additional
tries before locking out. To
reset after a lockout, turn
power switch (S1) OFF then
ON.
4. Oven reaches set temperature and controlling
thermostat opens.
A. Heat light goes out.
B. Power removed from heat relay (R3).