Vulcan-Hart VC4GC User manual

A product of VULCAN-HART LOUISVILLE, KY 40201-0696
F24682 (Rev. B, October 2007)
VC4GD WITH ROAST & HOLD SHOWN
SERVICE MANUAL
VC4G & VC6G SERIES
FULL SIZE
GAS CONVECTION OVENS
MODEL ML
VC4GS 126610
VC4GD 126611
VC4GC 136494
VC6GS 126612
VC6GD 126613
VC6GC 136495
- NOTICE -
This Manual is prepared for the use of trained Vulcan Service
Technicians and should not be used by those not properly qualified. If
you have attended a Vulcan Service School for this product, you may be
qualified to perform all the procedures described in this manual.
This manual is not intended to be all encompassing. If you have not
attended a Vulcan Service School for this product, you should read, in
its entirety, the repair procedure you wish to perform to determine if you
have the necessary tools, instruments and skills required to perform the
procedure. Procedures for which you do not have the necessary tools,
instruments and skills should be performed by a trained Vulcan Service
Technician.
Reproduction or other use of this Manual, without the express written
consent of Vulcan, is prohibited.
For additional information on Vulcan-Hart Company or to locate an authorized parts
and service provider in your area, visit our website at www.vulcanhart.com.

FULL SIZE GAS CONVECTION OVENS
F24682 (Rev. B, October 2007) Page 2 of 68
TABLE OF CONTENTS
GENERAL ................................................................................ 4
Introduction ............................................................................ 4
Installation ............................................................................ 4
Operation ............................................................................. 4
Cleaning .............................................................................. 4
Lubrication ............................................................................ 4
Specifications .......................................................................... 4
Tools................................................................................. 4
REMOVALANDREPLACEMENTOFPARTS .................................................... 5
Covers and Panels ...................................................................... 5
Control Panel Components ............................................................... 6
Component Panel Components ............................................................ 7
Temperature Probe (VC4GD/6GD) ......................................................... 8
GasBurner ............................................................................ 8
GasOrifice ............................................................................ 9
Gas Solenoid Valve ..................................................................... 9
Ignition Control Module .................................................................. 10
Spark Igniter and Flame Sense ........................................................... 10
Blower and Motor ...................................................................... 11
Oven Doors and Bearings (Independent Doors) .............................................. 12
Oven Doors (Simultaneous Doors) ......................................................... 13
RollerLatchAssembly .................................................................. 14
Door Catch Ball Assembly (Independent Doors) .............................................. 15
Door Window ......................................................................... 15
DoorSwitch .......................................................................... 16
Mechanical KX Thermostat (VC4GS/6GS) ................................................... 16
HighLimitThermostat .................................................................. 16
InteriorLights ......................................................................... 17
CoolingFan .......................................................................... 18
Service Procedures and Adjustments .......................................................... 19
SolidStateTemperatureControlCalibration(VC4GD/6GD) ..................................... 19
Mechanical Thermostat Calibration (VC4GS/6GS) ............................................ 20
SolidStateTemperatureControlTest(VC4GD/6GD) .......................................... 20
Temperature Probe Test (VC4GD/6GD) .................................................... 21
GasPressureAdjustment................................................................ 22
VerificationofSparkatIgnitor ............................................................ 23
DoorSwitchAdjustment ................................................................. 23
BlowerAdjustment ..................................................................... 24
DoorAdjustment....................................................................... 25
Door Strike Adjustment (Independent Doors) ................................................. 25
Door Catch Ball Adjustment (Independent Doors) ............................................. 26
Door Chain Adjustment (Simultaneous Doors) ................................................ 27

FULL SIZE GAS CONVECTION OVENS
F24682 (Rev. B, October 2007)Page 3 of 68
ComputerControl(VC4GC/VC6GC) ....................................................... 28
ComputerControlCalibration(VC4GC/VC6GC) .............................................. 29
ELECTRICALOPERATION .................................................................. 30
Component Function ................................................................... 30
Component Location ................................................................... 32
Sequence of Operation .................................................................. 37
VC4GS, VC6GS With Roast & Hold Option (Mechanical KX Thermostat) ....................... 37
VC4GD,VC6GDWithRoast&HoldOption(SolidStateTemperatureControl) .................. 41
CoolDownCycle(SolidStateTemperatureControl) ....................................... 46
VC4GC, VC6GC (Roast & Hold Standard on Computer Model) .............................. 46
Cool Down Cycle (Computer Control Model) ............................................. 49
Schematics ........................................................................... 50
VC4GS, VC6GS Mechanical (KX) Controls .............................................. 50
VC4GS, VC6GS Mechanical (KX) Controls, Roast & Hold Option ............................. 51
VC4GD,VC6GDSolidStateTemperatureControl ........................................ 52
VC4GD,VC6GDSolidStateTemperatureControl,Roast&HoldOption ....................... 53
VC4GC, VC6GC Computer Control (Roast & Hold Standard) ................................ 54
WiringDiagrams ....................................................................... 56
VC4GS, VC6GS Mechanical (KX) Controls .............................................. 56
VC4GS, VC6GS Mechanical (KX) Controls, Roast & Hold Option ............................. 58
VC4GD,VC6GDSolidStateTemperatureControl ........................................ 60
VC4GD,VC6GDSolidStateTemperatureControl,Roast&HoldOption ....................... 62
VC4GC, VC6GC Computer Control (Roast & Hold Standard) ................................ 64
TROUBLESHOOTING ...................................................................... 66
All Models ............................................................................ 66
Computer Control Models Only ........................................................... 67
© Vulcan 2007

FULL SIZE GAS CONVECTION OVEN - GENERAL
F24682 (Rev. B, October 2007) Page 4 of 68
GENERAL
INTRODUCTION
Procedures in this manual will apply to all models unless specified. Pictures and illustrations can be of any model
unless the picture or illustration needs to be model specific.
Models
MODEL
FEATURES OPTIONS
CAVITY
DEPTH
TEMPERATURE
CONTROL
DOORS
(50/50)
NORMAL
(ROAST)
TIMER
NORMAL
TIMER OR
HOLD
TIMER
ROAST
&
HOLD
BLOWER
208/240/60/1
VC4GS 26.5" Mechanical (KX) Independent 1, 2 1-Hour Dial 5-Hour Dial Optional Optional
VC6GS 30.5" Mechanical (KX) Independent 1, 2 1-Hour Dial 5-Hour Dial Optional Optional
VC4GD 26.5" Solid State Independent 1, 3 1-Hour Dial 5-Hour Dial Optional Optional
VC6GD 30.5" Solid State Independent 1, 3 1-Hour Dial 5-Hour Dial Optional Optional
VC4GC 26.5" Computer Independent 1, 3 24-Hour Digital Built in Built in Optional
VC6GC 30.5" Computer Independent 1, 3 24-Hour Digital Built in Built in Optional
1. Simultaneous doors are optional (with or w/o window).
2. Stainless steel doors w/o window (standard).
3. Stainless steel doors with window (standard).
INSTALLATION
Refer to the Installation and Operation Manual for
detailed installation instructions on single or stacked
ovens.
OPERATION
Refer to the Installation and Operation Manual for
specific operating instructions.
CLEANING
Refer to the Installation and Operation Manual for
specific cleaning instructions.
LUBRICATION
!Cavity blower motor has sealed bearings and
requires no additional lubrication.
!Huskey’s TF1000 grease or equivalent high
temperature Teflon grease.
SPECIFICATIONS
Electrical
Voltage - 120/60/1
Amps - 9.0 Amps
Input BTU Rating
Natural Gas - 44,000 BTU input at 3.5 in. W.C.
Propane Gas - 44,000 BTU input at 10.0 in. W.C.
Gas Line Pressures
Natural - Recommend (in. W.C.) 7.0, Min 5.0
Propane - Recommend (in. W.C.) 11.0, Min 11.0
Maximum 14.0 in. W.C. (Nat. or Prop.)
TOOLS
Standard
!Standard set of hand tools.
!VOM with A.C. current tester (Any quality VOM
with a sensitivity of at least 20,000 ohms per
volt can be used).
!Gear Puller to remove blower
Special
!Temperature tester (thermocouple type).
!Manometer

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 5 of 68
REMOVAL AND REPLACEMENT OF PARTS
COVERS AND PANELS
Top Front Cover
1. The top front cover is secured with four (4)
screws, two on each side of cover. Remove
these screws then remove the cover from the
oven.
2. Reverse the procedure to install.
Bottom Front Cover
1. The bottom front cover is secured with four (4)
screws, two on each side of cover. Remove
these screws then remove the cover from the
oven.
2. Reverse the procedure to install.
Control Panel
1. Remove three (3) screws on the right side
which secure the control panel then pull the
panel away from the oven.
NOTE: If the oven has a mechanical (KX type)
thermostat, it must be removed from the control
panel first, before removing the control panel.
2. Disconnect the temperature probe leads from
the solid state temperature control.
3. Unplug the wire harness connector to the
control panel components.
4. Reverse the procedure to install.
Right Side Panel
1. Remove the screws which secure the right side
of the top front cover, bottom front cover and
control panel.
2. Remove the remaining six screws securing the
right side panel.
3. Pull the right side panel out at the bottom then
down to remove.
4. Reverse the procedure to install.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 6 of 68
CONTROL PANEL
COMPONENTS
Removable Components Procedure
1. Remove the control panel as outlined under
COVERS AND PANELS.
2. Remove the component being replaced.
3. Reverse the procedure to install the
replacement component, then check oven for
proper operation.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 7 of 68
COMPONENT PANEL
COMPONENTS
Removable Components Procedure
1. Remove the right side panel as outlined under
COVERS AND PANELS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Disconnect the wire leads to the component
being replaced.
3. Remove the component.
4. Reverse the procedure to install the
replacement component and check oven for
proper operation.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 8 of 68
TEMPERATURE PROBE
(VC4GD/6GD)
1. Remove the right side panel as outlined under
COVERS AND PANELS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Disconnect the probe leads from the
temperature control.
3. Remove the racks and right rack support.
4. Remove probe clips from probe.
5. Push the probe through the opening in cavity
side wall and into the control panel area.
NOTE: The hole in the oven cavity wall does not line
up straight with the oven cavity outer shell, therefore
the probe must be removed at an angle.
6. Reverse the procedure to install the
replacement probe.
7. Adjust the temperature control as outlined under
SOLID STATE TEMPERATURE CONTROL
CALIBRATION (VC4GD/6GD) in SERVICE
PROCEDURES AND ADJUSTMENTS.
GAS BURNER
Shut off the gas before servicing
the unit.
1. Remove the lower front cover as outlined under
COVERS AND PANELS.
2. Disconnect the ignition cable and the flame
sense lead wire.
3. Remove the bolts securing the gas manifold
and place manifold aside.
4. Remove the screws securing the burner cover
then lift out.
5. Grasp the burner and lift out.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 9 of 68
6. Reverse procedure to install the replacement
burner.
NOTE: Ensure that burner positioning bracket (U
shaped end) is inserted into slot at the rear of the
burner chamber.
7. Check for proper operation.
GAS ORIFICE
Shut off the gas before servicing
the unit.
1. Remove the bottom front cover as outlined
under COVERS AND PANELS.
2. Remove the bolts securing the gas manifold to
the oven and place the manifold to the side.
3. Remove the gas orifice from the spud on the
manifold and replace with the correct orifice for
the given altitude.
4. Reverse procedure to install and check for
proper operation.
GAS SOLENOID VALVE
Shut off the gas before servicing
the unit.
All gas joints disturbed during
servicing must be checked for leaks. Check with
a soap and water solution (bubbles). Do not use
an open flame.
1. Remove the control panel and the right side
panel as outlined under COVERS AND
PANELS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Disconnect the lead wires.
3. Disconnect the compression fittings to the
valve.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 10 of 68
4. Loosen the bolts securing the valve and bracket
assembly then remove the screws securing the
valve to the bracket.
5. Reverse the procedure to install the
replacement gas valve.
NOTE: Clean the pipe threads and apply pipe joint
compound to threads. Any pipe joint compound
used, must be resistant to the action of propane
gases.
6. Verify gas pressure as outlined under GAS
PRESSURE ADJUSTMENT in SERVICE
PROCEDURES AND ADJUSTMENTS and
check for proper operation.
IGNITION CONTROL MODULE
Shut off the gas before servicing
the unit.
1. Remove the right side panel as outlined under
COVERS AND PANELS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Loosen the screws securing the mounting
bracket to the component panel and remove the
bracket.
3. Disconnect the lead wires and igniter cable from
the ignition module board.
4. Remove the ignition module board from the
mounting bracket.
5. Reverse the procedure to install the
replacement ignition module board.
SPARK IGNITER AND
FLAME SENSE
Shut off the gas before servicing
the unit.
1. Remove the gas burner as outlined under GAS
BURNER.
2. Remove the screws securing the ignitor and
flame sense to burner then remove the
assembly.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 11 of 68
3. Reverse the procedure to install the assembly
and check for proper operation.
NOTE: Check to ensure the spark gap distance is
approximately 1/8". If the gap appears to be
excessive or poor sparking is occurring then adjust.
BLOWER AND MOTOR
Shut off the gas before servicing
the unit.
1. Take out the racks and rack supports.
2. Remove screws securing the SNORKEL and
remove the snorkel.
3. Remove screws securing baffle panel and
remove the panel.
4. If replacing:
A. Blower Only - Loosen set screws on blower
hub and using a bearing puller, remove
blower from motor shaft.
1) Reverse procedure to install and
adjust blower position as outlined
under BLOWER ADJUSTMENT in
SERVICE PROCEDURES AND
ADJUSTMENTS.
B. Motor - perform step 4A and continue
procedure.
5. Remove the screws securing the air baffle to
the rear wall at the lower right hand corner.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 12 of 68
6. Remove the nuts that secure the motor
mounting plate to the rear wall.
Place a piece of cardboard on the bottom of the oven
cavity to protect its surface from any damage during
motor assembly removal.
7. Pull the motor assembly into the oven cavity
and place it on the cardboard.
8. Remove the junction box cover from the motor,
disconnect lead wires and remove the conduit.
9. Remove motor mounting bolts and flat washers
then lift the motor from the mounting plate.
10. Position the replacement motor on the motor
mounting plate and install mounting bolts and
washers. Hand tighten mounting bolts only.
11. Reconnect lead wires at the motor, replace
conduit and junction box cover.
NOTE: Check data plate on motor for wiring
schematic. The motor must rotate clockwise when
viewed from the shaft end.
12. Slide blower onto motor shaft until hub is flush
with end of shaft then tighten set screws.
13. Adjust motor position until blower is parallel to
motor mounting plate as outlined under
BLOWER ADJUSTMENT in SERVICE
PROCEDURES AND ADJUSTMENTS.
14. Position motor mounting plate on the rear wall
and secure with nuts and washers.
15. Replace the baffle panel and SNORKEL.
16. Replace the air baffle on the rear wall at the
lower right hand corner.
17. Remove cardboard from the bottom of the oven
cavity.
18. Install rack guides and racks.
19. Check oven for proper operation.
OVEN DOORS AND BEARINGS
(INDEPENDENT DOORS)
1. Remove the top front cover and bottom front
cover as outlined under COVERS AND
PANELS.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 13 of 68
2. Remove the door switch lever.
3. Remove the lower door seal strip to expose the
mounting screws of the door assembly.
4. Remove the two (2) lower sill bolts by the lower
door shaft and the four (4) counter-sunk screws
from the lower sill.
NOTE: The door assembly is heavy and will drop
down once the last screw is removed. If removing
door assembly with-out assistance, the ignition
cable, flame sense lead and gas manifold should
also be removed to avoid damage to these
components.
5. Tilt the top of the door slightly forward and lift
the door up until the bottom of the door shaft
clears the opening in the sill.
6. Lay the door flat to prevent damage.
7. The top and bottom bearings are now
accessible for inspection and/or replacement if
needed.
A. If bearings are ok, proceed to step 8.
B. If replacing the top bearing, remove the top
bearing retainer and top bearing.
C. If replacing the bottom bearing, remove it
from the door shaft or the lower sill
opening.
8. Reverse procedure to install door assembly and
check for proper adjustment as outlined under
DOOR ADJUSTMENT and DOOR SWITCH
ADJUSTMENT in SERVICE PROCEDURES
AND ADJUSTMENTS.
OVEN DOORS
(SIMULTANEOUS DOORS)
Assembly Removal
1. Remove the top front cover and bottom front
cover as outlined under COVERS AND
PANELS.
2. Remove the door switch lever.
3. Remove the top bearing retainers and top
bearings.
4. Remove the lower door seal strip to expose the
mounting screws of the door assembly.
A. Remove the two (2) lower sill bolts by the
lower door shaft and the four (4)
counter-sunk screws from the lower sill.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 14 of 68
NOTE: The door assembly is heavy and will drop
down once the last screw is removed. If removing
door assembly with-out assistance, the ignition
cable, flame sense lead and gas manifold should
also be removed to avoid damage to these
components.
5. Lift up on the door assembly and swing the right
side out then move the assembly to the left to
clear the slots in the upper door sill.
6. Lay the door assembly on a flat cushioned
surface for disassembly.
7. Reverse procedure to install door assembly and
check for proper adjustment as outlined under
DOOR ADJUSTMENT, DOOR CHAIN
ADJUSTMENT (SIMULTANEOUS DOORS)
and DOOR SWITCH ADJUSTMENT in
SERVICE PROCEDURES AND
ADJUSTMENTS.
Disassembly
1. Remove the door assembly as outlined in
OVEN DOORS (SIMULTANEOUS) under
ASSEMBLY REMOVAL.
2. Remove the door chain by loosening one of the
turnbuckles.
3. Loosen the set screw on the sprocket of door
being replaced.
4. Drive out the spiral pin from the sprocket of door
being replaced.
5. Remove the door from lower sill bearings and
sprocket.
A. Door assembly parts are now accessible
for inspection and/or replacement if
necessary.
6. Reverse procedure to re-assemble the door
assembly parts and check for proper adjustment
as outlined under DOOR CHAIN ADJUSTMENT
(SIMULTANEOUS DOORS) in SERVICE
PROCEDURES AND ADJUSTMENTS.
ROLLER LATCH ASSEMBLY
(INDEPENDENT DOORS)
NOTE: For units with serial number starting with 48
made after 8/12/07 and serial number starting with
54 made after 8/26/07.
1. Remove the screws that attach roller latch
assembly to door.
2. Reverse procedure to install.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 15 of 68
DOOR CATCH BALL ASSEMBLY
(INDEPENDENT DOORS)
NOTE: For units with serial number starting with 48
made before 8/13/07 and serial number starting with
54 made before 8/27/07.
1. Remove the top front cover as outlined under
COVERS AND PANELS.
2. Remove the screws that secure the door catch
assembly.
3. Reverse procedure to install.
4. Adjust the ball catch as outlined under DOOR
CATCH BALL ADJUSTMENT (INDEPENDENT
DOORS) in SERVICE PROCEDURES AND
ADJUSTMENTS.
DOOR WINDOW
1. Remove the screws at the top and bottom of
door.
2. Independent doors:
A. Remove the door handle then remove the
outer door panel.
B. Lift out the inner door panel and window
assembly.
NOTE: Left door only - remove door seal from
the inside edge of the door.
3. Simultaneous doors:
A. If replacing window on the left door,
remove the handle from the front of the
door then remove door seal from the inside
edge of the door.
1) Lift out the inner door panel and
window assembly.
2) If replacing window on the right door,
remove the screws along the inside
edge (if applicable) of the door then
remove the inner door panel and
window assembly.
4. Remove the screws securing the window TABS
to the door bracket and lift the window assembly
out from the door frame.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007) Page 16 of 68
5. Reverse procedure to install the replacement
window.
DOOR SWITCH
1. Remove the top front cover as outlined under
COVERS AND PANELS.
2. Disconnect the lead wires to the door switch.
3. Remove the switch.
4. Reverse procedure to install the replacement
switch and check for proper adjustment as
outlined under DOOR SWITCH ADJUSTMENT
in SERVICE PROCEDURES AND
ADJUSTMENTS.
MECHANICAL KX THERMOSTAT
(VC4GS/6GS)
1. Remove the racks and right rack support.
2. Remove the thermostat knob and mounting
screws from the control panel and then remove
the control panel.
3. Remove the probe guard from the oven cavity
wall.
NOTE: When installing, the probe should not extend
beyond the probe guard.
4. Remove the thermostat bulb from the oven
cavity by pushing it through the oven wall and
into the control panel area.
NOTE: The hole in the oven cavity wall does not line
up straight with the oven cavity outer shell, therefore
the probe must be removed at an angle.
5. Reverse the procedure to install.
6. Adjust the thermostat as outlined under
MECHANICAL THERMOSTAT CALIBRATION
(VC4GS/6GS) in SERVICE PROCEDURES
AND ADJUSTMENTS.
HIGH LIMIT THERMOSTAT
1. Take out racks from the oven.
2. Remove the high limit thermostat
cover/mounting plate from inside the oven
cavity at the top.

FULL SIZE GAS CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
F24682 (Rev. B, October 2007)Page 17 of 68
3. Disconnect lead wires from high limit thermostat
then remove high limit thermostat from
cover/mounting plate.
NOTE: Remove the old RTV from the cover and
mating surfaces inside the oven cavity and apply
new RTV before installing.
4. Reverse procedure to install.
INTERIOR LIGHTS
Lamp
1. Remove the racks.
2. Unscrew the glass lens for the light being
replaced then unscrew the bulb.
3. Replace bulb then reverse the procedure to
install.
Lamp Assembly
1. Remove the lens and bulb.
2. Remove the springs from the retaining tabs (2
places) on the socket.
3. Depress the retaining tabs and pull the socket
out from the oven, far enough to disconnect the
lead wires.
4. Remove the socket from the oven.
5. Attach the lead wires to the replacement socket.
6. Insert the socket into the hole in the oven and
push until the socket is held in place by the
retaining tabs.
7. Install the light bulb and lens.
8. Check for proper operation.

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F24682 (Rev. B, October 2007) Page 18 of 68
COOLING FAN
1. Remove the right side panel as outlined under
COVERS AND PANELS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Disconnect the lead wires to the fan motor by
removing wire nuts.
3. Remove the screws securing the air deflector to
the fan then loosen the tab screw holding the
fan to the component panel. Rotate the tab so
that the fan will clear and remove the fan.
4. Reverse the procedure to install the
replacement fan and check for proper operation.
NOTE: The fan must be installed so air is pulled from
the rear of the oven and blown into the control area.
The arrow on the fan body indicates AIR FLOW
direction and should be pointing toward the controls.
NOTE: Ensure fan is seated SQUARELY against the
air tube and the oven bottom.
NOTE: The air deflector should be angled upwards
at approximately 30 degrees to properly direct the air
flow.

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F24682 (Rev. B, October 2007)Page 19 of 68
SERVICE PROCEDURES AND ADJUSTMENTS
Certain procedures in this section require electrical test or measurements while power is
applied to the machine. Exercise extreme caution at all times. If test points are not easily accessible,
disconnect power and follow lockout / tagout procedures, attach test equipment and reapply power to
test.
SOLID STATE TEMPERATURE
CONTROL CALIBRATION
(VC4GD/6GD)
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the ON-OFF-COOL DOWN switch to ON.
3. Set the temperature control dial to 350°F.
4. Allow the oven temperature to stabilize
(normally 3 cycles).
5. Record the temperature at which the Heat lamp
goes OFF and comes ON for at least two
complete heating cycles.
6. Calculate the differential by subtracting the
temperature indicated when the lamp goes out
from the temperature indicated when the lamp
comes on.
A. The differential calculated should be less
than 20 °F.
1) If the differential is less than 20 °F, the
temperature control circuit is
functioning properly.
a. Proceed to step 7.
2) If the differential is more than 20 °F:
a. Check the temperature probe as
outlined under TEMPERATURE
PROBE TEST (VC4GD/6GD).
b. If the probe is functioning
properly then temperature control
is malfunctioning.
a) Install a replacement
temperature control and
check calibration.
7. Calculate the average temperature by adding
the temperature indicated when the lamp goes
out to the temperature indicated when the lamp
comes on and dividing this answer by 2.
A. If the average temperature is less than
10 °F from the dial setting, the thermostat
is properly calibrated.
B. If the average temperature is more than
10 °F from the dial setting, the thermostat
calibration must be adjusted.
1) Loosen the temperature control knob
set screw and remove the knob from
the stem.
2) Loosen temperature control mounting
screws only enough to rotate the
control.
a. Place thumb and forefinger on
the head of the mounting screws,
apply pressure and slightly rotate
the screw heads (body of control)
in the slot. Rotate clockwise to
increase temperature and
counterclockwise to decrease.
b. Center the stem in the opening
and re-tighten the temperature
control mounting screws.
c. Replace knob and re-tighten set
screw .
d. Rotate the knob to the lowest
temperature setting then back to
350°F.
e. Repeat the average temperature
calculation in step 7.
NOTE: Allow the oven to cycle at
least two times between
adjustments before performing
the calculation.
a) If the average temperature
still differs more than 10 °F
from the dial setting, adjust
the thermostat calibration
until the average
temperature is within
tolerance.
C. If the above adjustment cannot be
obtained, replace the temperature control
and check calibration.

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F24682 (Rev. B, October 2007) Page 20 of 68
MECHANICAL THERMOSTAT
CALIBRATION (VC4GS/6GS)
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the ON-OFF-COOL DOWN switch to ON.
3. Set the thermostat dial to 350°F.
4. Allow the oven temperature to stabilize
(normally 3 cycles).
5. Record the temperature when the thermostat
cycles OFF and ON for at least three complete
cycles.
6. Calculate the differential by subtracting the
temperature indicated when heat lamp goes out
from temperature indicated when heat lamp
comes on.
A. The differential calculated should be less
than 30EF.
1) If the differential is less than 30° F, the
thermostat is functioning properly.
a. Proceed to step 7.
2) If the differential is more than 30EF,
the thermostat is malfunctioning.
a. Install a replacement thermostat
and check calibration.
7. Calculate the average temperature by adding
the temperature indicated when the heat lamp
goes out to the temperature indicated when the
heat lamp comes on and dividing this answer by
2.
A. If the average temperature is less than
15EF from the dial setting, the thermostat is
properly calibrated.
B. If the average temperature is more than
15EF of the dial setting, the thermostat
calibration must be adjusted.
1) Remove the thermostat knob.
2) Hold the thermostat shaft and turn the
inner set screw clockwise to decrease
temperature or counterclockwise to
increase temperature (1/4 turn =
35EF).
8. Replace the knob and repeat step 7 until the
average temperature is within tolerance.
NOTE: Allow the oven to cycle at least two times
between adjustments before performing the
calculation.
9. If the above adjustment can not be obtained,
install a replacement thermostat and check
calibration.
SOLID STATE TEMPERATURE
CONTROL TEST (VC4GD/6GD)
1. Remove the right side panel as outlined under
COVERS AND PANELS in REMOVAL AND
REPLACEMENT OF PARTS.
NOTE: If right side panel is not accessible, this
component can be serviced by removing the control
panel as outlined under COVERS AND PANELS.
2. Place a thermocouple in the geometric center of
the oven cavity.
NOTE: Oven temperature must be below 450°.
NOTE: If oven is equipped with the Roast and Hold
option, turn it to Normal ROAST (normal cooking)
before continuing.
3. Set the temperature control to the maximum
setting.