Page 1
SERVICE MANUAL
HALF-SIZE CONVECTION OVENS
ELECTRIC ECO2D ML-114570
ECO2C ML-114572
GAS GCO2D ML-114573
GCO2C ML-114571
- NOTICE -
This Manual is prepared for the use of trained Hobart Service
Technicians and should not be used by those not properly
qualified.
This manual is not intended to be all encompassing. If you have
not attended a Hobart 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 Hobart Service Technician.
The reproduction, transfer, sale or other use of this manual,
without the express written consent of Hobart, is prohibited.
This manual has been provided to you by ITW Food Equipment
Group LLC ("ITW FEG") without charge and remains the property
of ITW FEG, and by accepting this manual you agree that you will
return it to ITW FEG promptly upon its request for such return at
any time in the future.
A product of Vulcan-Hart 3600 North Point Blvd Baltimore, MD 21222
F24575 Rev. A (0619)
Page 2
HALF-SIZE CONVECTION OVENS
TABLE OF CONTENTS
SERVICE UPDATES ....................................................................................... 4
SERVICE UPDATES ................................................................................... 4
TIS DOCUMENT LIST - HALF SIZE CONVECTION OVENS ............................................. 4
GENERAL .................................................................................................. 6
INTRODUCTION ....................................................................................... 6
GENERAL .......................................................................................... 6
SPECIFICATIONS ...................................................................................... 6
TOOLS ................................................................................................. 6
REMOVAL AND REPLACEMENT OF PARTS ............................................................... 7
COVERS AND PANELS ................................................................................ 7
TOP FRONT COVER ............................................................................... 7
CONTROL PANEL ................................................................................. 7
RIGHT SIDE PANEL ................................................................................ 7
CONTROL PANEL COMPONENTS ..................................................................... 7
REMOVABLE COMPONENTS ...................................................................... 7
PROCEDURE ...................................................................................... 7
BLOWER AND/OR BLOWER MOTOR (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) ........... 8
BLOWER AND/OR BLOWER MOTOR (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) ........... 9
HEAT EXCHANGER (GAS OVENS) ................................................................... 10
BURNER (GAS OVENS UP TO S/N GAS: 481929306) ................................................. 11
BURNER (AFTER S/N GAS: 481929307) .............................................................. 12
GAS VALVE (SOLENOID) (GAS OVENS) .............................................................. 13
HEATING ELEMENTS (ELECTRIC OVENS) ........................................................... 13
TEMPERATURE PROBE .............................................................................. 14
OVEN DOOR (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) ................................... 14
REMOVAL ........................................................................................ 14
DISASSEMBLY ................................................................................... 15
OVEN DOOR (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) .................................. 15
DOOR CHAIN ADJUSTMENT (SIMULATANEOUS DOORS) ........................................... 16
DOOR SWITCH (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) ................................ 16
DOOR SWITCH (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) ................................ 17
SERVICE PROCEDURES AND ADJUSTMENTS ........................................................... 18
TEMPERATURE PROBE TEST (ALL MODELS) ....................................................... 18
VERIFICATION OF SPARK AT SPARK PROBE ........................................................ 18
GAS PRESSURE ADJUSTMENT ...................................................................... 19
SPARK IGNITION CONTROL TEST ................................................................... 19
NO GAS IGNITION & NO SPARKING .............................................................. 20
NO GAS IGNITION & NO SPARKING .............................................................. 20
SOLID STATE CONTROL TEST ....................................................................... 20
SOLID STATE CONTROL CALIBRATION .............................................................. 21
DOOR SWITCH ADJUSTMENT (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) ................ 22
DOOR SWITCH ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) ................ 22
DOOR REVERSAL .................................................................................... 23
DOOR ADJUSTMENT (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) .......................... 24
DOOR ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) ......................... 24
BLOWER ADJUSTMENT (UP TO S/N GAS: 481929306 ELECTRIC: 481929289) ....................... 25
BLOWER ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290) ...................... 25
ELECTRONIC CONTROL ............................................................................. 25
HEATING ELEMENT TEST ............................................................................ 26
ELECTRICAL OPERATION ................................................................................ 27
COMPONENT FUNCTION ............................................................................ 27
COMPONENT LOCATION ............................................................................. 27
SEQUENCE OF OPERATION - GAS OVEN ........................................................... 29
F24575 Rev. A (0619) Page 2 of 50
Page 3
HALF-SIZE CONVECTION OVENS
IGNITION MODULE ............................................................................... 29
SOLID STATE CONTROL ......................................................................... 29
ELECTRONIC CONTROL ......................................................................... 30
COOLDOWN ...................................................................................... 30
SEQUENCE OF OPERATION - ELECTRIC OVEN ..................................................... 31
SOLID STATE CONTROL ......................................................................... 31
ELECTRONIC CONTROL ......................................................................... 31
COOLDOWN ...................................................................................... 32
SCHEMATICS GAS OVENS ........................................................................... 33
WIRING DIAGRAM - GAS OVENS ..................................................................... 36
SCHEMATICS - ELECTRIC OVENS ................................................................... 41
WIRING DIAGRAM - ELECTRIC OVENS .............................................................. 44
TROUBLESHOOTING ..................................................................................... 49
ELECTRIC OVENS .................................................................................... 49
GAS OVENS .......................................................................................... 49
© VULCAN 2019
Page 3 of 50 F24575 Rev. A (0619)
Page 4
HALF-SIZE CONVECTION OVENS - SERVICE UPDATES
SERVICE UPDATES
SERVICE UPDATES
June 2019
• Updated SPECIFICATIONS.
• Added BLOWER AND/OR BLOWER MOTOR (AFTER S/N GAS: 481929307 ELECTRIC: 481929290)
• Added BURNER (AFTER S/N GAS: 481929307).
• Added OVEN DOOR (AFTER S/N GAS: 481929307 ELECTRIC: 481929290).
• Added DOOR SWITCH (AFTER S/N GAS: 481929307 ELECTRIC: 481929290).
• Added DOOR SWITCH ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290).
• Added DOOR ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290).
• Added BLOWER ADJUSTMENT (AFTER S/N GAS: 481929307 ELECTRIC: 481929290).
• Updated SCHEMATICS GAS OVENS.
• Updated WIRING DIAGRAM - GAS OVENS.
• Updated SCHEMATICS - ELECTRIC OVENS.
• Updated WIRING DIAGRAM - ELECTRIC OVENS.
TIS DOCUMENT LIST - HALF SIZE CONVECTION OVENS
SERVICE TAB
Document Title Document Type
Half Size Convection Ovens and Gas Service Manual Service Manual
Setting the Igniter Gap Service Kit Instructions (SKI)
Gas Connections & BTU Flow Capacity Technical Service Bulletin (TSB)
Machine Data Code Information Technical Service Bulletin (TSB)
SERVICE TAB (Multimedia)
Document Title Document Type
3700 Oven Quick Start Guide Operator
HCEC20 & HEC20D Electric Convection Ovens (ML's 114574 & 114576)
Instructions
Repair Flood-Damaged Equipment Misc
Convection Oven Computer Control Guide Operator
Convection Ovens Gas & Electric Service Instructions
Stand Instructions - Half Size Convection Oven Service Instructions
Rating Plate Locations on Current Vulcan-Hart/Wolf Range Equipment Technical Service Bulletin (TSB)
SB770R Door Latch Change on Full Size Convection Ovens (VC4, VC6,
SG, WKG, & WKE)
Instructions
Technical Service Bulletin (TSB)
F24575 Rev. A (0619) Page 4 of 50
Page 5
HALF-SIZE CONVECTION OVENS - SERVICE UPDATES
SERVICE TAB (Multimedia)
SB880 Independent Door Handle Assembly for Convection Ovens Technical Service Bulletin (TSB)
TSB 1037A Hobart to Vulcan "Common" Model Cross Reference List Technical Service Bulletin (TSB)
TSB 0874 Full Size Convection Ovens - Lighting & Cooling Fan Technical Service Bulletin (TSB)
TSB 0930 Gas Convection Ovens, Blower Motor & Wheel Change Technical Service Bulletin (TSB)
TSB 1004E All Half Size & Full Size Unites w/Independent Opening Doors
-Enhanced Door Catch Info.
TSB 1290 HEC. HGC, VEC, VGC Conveyor Ovens - New Temperature
Control
PARTS TAB
Document Title Document Type
Half Size Electric Convection Ovens Parts Catalog Parts Catalog
Technical Service Bulletin (TSB)
Technical Service Bulletin (TSB)
Page 5 of 50 F24575 Rev. A (0619)
Page 6
HALF-SIZE CONVECTION OVENS - GENERAL
GENERAL
INTRODUCTION
General
This manual will cover half-size electric and gas
convection ovens that use either a solid state control
or an electronic control.
Procedures in this manual are applicable to both gas
and electric ovens unless specified.
SPECIFICATIONS
GAS OVENS
GAS DATA ELECTRICAL DATA
INPUT BTU/HR MANIFOLD PRESSURE
NATURAL PROPANE NATURAL PROPANE 120V
SINGLE OVEN 2500 2500 3.5" W.C. 10" W.C. 950 8
SINGLE OVEN 5000 5000 3.5" W.C. 10" W.C. 1900 16
ELECTRIC OVENS
NOMINAL AMPS PER LINE WIRE
3 PHASE 1 PHASE
208V 240V
SINGLE
OVEN
SINGLE
OVEN
3-PHASE LOADING
TOTAL
KW
5.5 2.5 0 3.0 22.9 10.4 12.5 19.9 9.0 10.9 26.5 23.0
11.0 5.0 0 6.0 45.8 20.8 25.0 39.7 18.0 21.7 52.9 45.9
(KW PER PHASE)
L1-L2 L2-L3 L1-L3 L1 L2 L3 L1 L2 L3
LOAD (Watts)
AMP/LINE
208V 240V
TOOLS
Standard
• Standard set of hand tools.
• VOM with minimum of NFPA-70E CATIII 600V, UL/CSA/TUV listed. Sensitivity of at least 20,000 ohms per
volt and the ability to measure DC micro amps. Meter leads must also be rated at CAT III 600V.
• Clamp on type amp meter with minimum of NFPA-70E CAT III 600V,UL/CSA/TUV listed.
• Temperature tester (thermocouple type).
• ESD (Electrostatic discharge) Protection Kit.
Special
• Hazardous gas leak tester.
• Manometer (Gas Ovens).
F24575 Rev. A (0619) Page 6 of 50
Page 7
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
REMOVAL AND REPLACEMENT OF PARTS
COVERS AND PANELS
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
Top Front Cover
1. The top front cover is secured with four screws,
two on each side of cover. Remove these screws
then pull cover off unit.
Fig. 1
2. Reverse the procedure to install.
3. Pull the panel away from the oven.
Fig. 3
4. Unplug the lead wires to the control panel
components and disconnect the temperature
probe leads.
5. Reverse the procedure to install.
Right Side Panel
1. Remove the three screws which secure the right
side of the control panel.
2. Loosen the two screws on the right side of the top
front cover.
3. Remove the remaining eight screws securing the
right side panel.
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.
Fig. 2
2. Reverse the procedure to install.
Control Panel
1. On gas models, remove the handle from the
manual gas valve.
2. Remove the three screws from the left front and
loosen the three screws on the right side of the
control panel.
Fig. 4
4. Pull the right side panel out at the bottom then
down to remove.
5. Reverse the procedure to install.
CONTROL PANEL COMPONENTS
Removable Components
Listed on the illustrations TSP1001C & TSP1046C
Procedure
1. Remove CONTROL PANEL COVER.
Page 7 of 50 F24575 Rev. A (0619)
Page 8
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
4. Reverse procedure to install.
5. Verify proper oven operation.
BLOWER AND/OR BLOWER
MOTOR (UP TO S/N GAS:
481929306 ELECTRIC: 481929289)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove racks and the right rack support.
2. Remove baffle panel by lifting up and out.
3. For gas ovens only, remove HEAT
EXCHANGER (GAS OVENS).
Fig. 5
Fig. 7
4. Loosen set screws on blower hub.
Fig. 6
2. Disconnect wire leads at the component to be
replaced.
3. Remove component.
F24575 Rev. A (0619) Page 8 of 50
Page 9
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
10. Install mounting pads and bolts. DO NOT tighten
mounting bolts.
11. Slide blower onto motor shaft until hub is flush
with end of shaft and tighten set screws .
12. Adjust motor position until blower is parallel to
oven cavity wall with a 1/4" spacing. Refer to:
BLOWER ADJUSTMENT (UP TO S/N GAS:
481929306 ELECTRIC: 481929289).
13. Tighten bolts.
14. Install baffle panel, rack guides and racks.
15. Verify proper oven operation.
Fig. 8
5. Remove blower from motor shaft.
NOTE: Bearing puller may be necessary.
If the blower only is to be replaced, reverse
procedure to install and perform BLOWER
ADJUSTMENT (UP TO S/N GAS: 481929306
ELECTRIC: 481929289).
6. Remove RIGHT SIDE PANEL.
7. Note and disconnect motor wires.
A. P1 (purple) to wire # 11.
B. Orange (low speed) to wire # 12.
C. Blue (high speed) to wire # 13.
D. Red wires connected together.
8. Remove motor mounting bolts securing motor to
mounting plate and remove from oven.
BLOWER AND/OR BLOWER
MOTOR (AFTER S/N GAS:
481929307 ELECTRIC: 481929290)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove racks and the right rack support.
2. Remove baffle panel by lifting up and out.
3. For gas ovens only, remove HEAT
EXCHANGER.
Fig. 9
9. Place new motor on mounting plage and route
wiring through grommet in component panel.
Fig. 10
4. Loosen set screws on blower hub.
Page 9 of 50 F24575 Rev. A (0619)
Page 10
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
Fig. 11
5. Remove blower from motor shaft.
NOTE: Bearing puller may be nesscessary.
If the blower only is to be replaced, reverse
procedure to install and perform BLOWER
ADJUSTMENT (UP TO S/N GAS: 481929306
ELECTRIC: 481929289).
13. Install baffle panel, rack guides and racks.
HEAT EXCHANGER (GAS OVENS)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
1. Remove racks and right rack support.
2. Remove baffle panel by lifting up and out.
3. Remove heat exchanger mounting screws and
remove from oven.
6. Remove RIGHT SIDE PANEL.
7. Note and disconnect motor wire connector.
8. Remove four nuts that secure motor to oven.
Fig. 12
9. Place new motor on studs and install nuts.
10. Install mounting pads and bolts. DO NOT tighten
mounting bolts.
11. Install blower with 1/4" spacing. Refer to
BLOWER ADJUSTMENT (UP TO S/N GAS:
481929306 ELECTRIC: 481929289).
12. Tighten bolts.
F24575 Rev. A (0619) Page 10 of 50
4. Reverse procedure to install.
5. Verify proper oven operation.
Fig. 13
Page 11
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
BURNER (GAS OVENS UP TO S/N
GAS: 481929306)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
1. Remove racks and the right rack support.
2. Remove baffle panel by lifting up and out.
3. Remove RIGHT SIDE PANEL.
Fig. 15
9. Remove inner right side.
4. Remove CONTROL PANEL.
5. Remove HEAT EXCHANGER.
6. Remove BLOWER AND/OR BLOWER MOTOR
(UP TO S/N GAS: 481929306 ELECTRIC:
481929289).
7. Remove motor mount cover (1, Fig. 14).
Fig. 14
Fig. 16
10. Remove burner.
8. Remove inner right hand side inside (1, Fig. 15)
and outer (2, Fig. 15) mounting screws.
Page 11 of 50 F24575 Rev. A (0619)
Page 12
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
BURNER (AFTER S/N GAS:
481929307)
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove RIGHT SIDE PANEL.
2. Remove nut holding orifice assembly (1, Fig.
Fig. 17
19).
11. Reverse procedure to install.
NOTE: When installed, the electrodes are positioned
toward the front of the oven.
Fig. 19
3. Disconnect lead wires to electrode assembly (2,
Fig. 19).
4. Remove burner assembly (1, Fig. 20) mounting
screws.
Fig. 18
12. Verify proper oven operation.
F24575 Rev. A (0619) Page 12 of 50
Fig. 20
Page 13
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
5. Pull burner assembly out.
6. Remove ignitor.
7. Reverse procedure to install.
8. Verify proper oven operation.
GAS VALVE (SOLENOID) (GAS
OVENS)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
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 RIGHT SIDE PANEL. .
2. Disconnect the lead wires at the gas valve.
3. Disconnect the gas line fitting going to the burner
at the top of the gas valve.
4. Remove the gas valve from the nipple between
the it and the manual gas valve.
Fig. 21
5. Reverse procedure to install.
6. Adjust the gas valve as outlined under “GAS
PRESSURE ADJUSTMENT”.
HEATING ELEMENTS (ELECTRIC
OVENS)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove racks and the right rack support.
2. Remove baffle panel by lifting up and out.
3. Remove the Right Side Panel as outlined under
“COVERS AND PANELS”.
4. Disconnect the lead wires to the heating
elements.
5. Remove the screws from the clamps that secure
the heating element assembly.
Page 13 of 50 F24575 Rev. A (0619)
Page 14
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
Fig. 23
NOTE: The probe may have to be inserted at an
angle. The hole in the inside oven cavity wall may not
line up straight with the oven cavity outer shell.
4. Reverse the procedure to install the new probe.
5. Adjust the temperature control as outlined under
SOLID STATE CONTROL CALIBRATION or
ELECTRONIC CONTROL in "SERVICE
PROCEDURES AND ADJUSTMENTS".
OVEN DOOR (UP TO S/N GAS:
481929306 ELECTRIC: 481929289)
Fig. 22
6. Pull the top of the heating element assembly into
the oven cavity until the ends of the elements are
inside the oven cavity. Lift up and remove the
lower clamp from between the side wall and the
bottom of the oven cavity.
7. Remove the clamps from the heating element
assembly and replace the element(s).
8. Reverse procedure to install.
TEMPERATURE PROBE
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove the Control Panel as outlined under
"COVERS AND PANELS".
2. Disconnect the probe leads at the temperature
control.
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Removal
1. Remove TOP FRONT COVER.
2. Remove door switch lever from door shaft.
3. Remove door switch bracket.
Fig. 24
4. While supporting the door, remove bearing, door
plate and spacer.
3. Remove probe from the probe guard and push it
thru the oven wall into the control panel area.
NOTE: When installing, only the metal surface of the
probe should be inserted into the probe guard.
F24575 Rev. A (0619) Page 14 of 50
Page 15
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
Fig. 25
5. Lift door from the lower bearing.
6. Reverse procedure to install door assembly and
check DOOR ADJUSTMENT (UP TO S/N GAS:
481929306 ELECTRIC: 481929289).
Disassembly
1. Open door.
2. Remove door handle and latch plate.
3. Remove screws which secure the inner and outer
door panels to door frame.
Fig. 27
6. Reverse procedure to install the new window and
perform
GAS: 481929306 ELECTRIC: 481929289).
DOOR ADJUSTMENT (UP TO S/N
OVEN DOOR (AFTER S/N GAS:
481929307 ELECTRIC: 481929290)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove TOP FRONT COVER and BOTTOM
COVER.
2. Remove door switch lever arm from door shaft.
Fig. 26
4. Remove inner and outer door panel.
5. Remove four screws and lift window assembly
out.
NOTE: Use high temperature silicone between the
window and the door panel.
Fig. 28
3. With door closed, support door while carefully
removing upper door support mounting screws.
Page 15 of 50 F24575 Rev. A (0619)
Page 16
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
Fig. 29
4. Slide upper door support bracket off door shaft.
5. Lift door out of lower door support.
6. Reverse procedure to install.
DOOR CHAIN ADJUSTMENT
(SIMULATANEOUS DOORS)
Introduction
When the oven doors are in proper adjustment,
as the doors come together, the right door will
lead the left door in closing by about 1/4 inch. The
doors will feel like they are self closing the last
1/2 inch of travel.
Procedure
1. Remove the lower sill cover.
2. Close doors and check door chain for factory
setting.
A. Turnbuckles should be 5 to 5 1/2 inches
apart.
B. Short eye bolt should be connected to the
end of the chain that goes to the front of the
sprocket.
C. 2 links of the chain should not be engaged
at the rear of the sprocket.
D. Chain must be tight enough that the doors
move simultaneously when opened or
closed.
Fig. 30
4. If right door does not lead the left door in closing:
A. Loosen locknuts on both turnbuckles.
B. Loosen left turnbuckle.
C. Tighten right turnbuckle.
D. Tighten locknuts on both turnbuckles.
5. If the right door leads the left door by more than
3/8 inch:
A. Loosen locknuts on both turnbuckles.
B. Loosen right turnbuckle.
C. Tighten left turnbuckle.
D. Tighten locknuts on both turnbuckles.
6. Check door for proper operation.
NOTE: The locknuts must be tight during testing or
the adjustment will not hold.
A. If doors do not close properly, repeat step 4,
5 and 6.
B. If doors operate properly, continue to step 7.
7. Install the lower front cover.
DOOR SWITCH (UP TO S/N GAS:
481929306 ELECTRIC: 481929289)
E. When the doors are opened, the
turnbuckles will move away from each other.
F. The stop cable must be positioned where it
moves freely and does not get pinched.
3. Position door chain assembly to factory setting if
the conditions in step 2 are not met.
F24575 Rev. A (0619) Page 16 of 50
1. Remove TOP FRONT COVER.
2. Disconnect the leads to door switch.
3. Remove switch mounting screws.
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Page 17
HALF-SIZE CONVECTION OVENS - REMOVAL AND REPLACEMENT OF PARTS
4. Remove switch which is secured by two screws.
Fig. 31
5. Reverse the procedure to install.
6. Perform DOOR SWITCH ADJUSTMENT.
DOOR SWITCH (AFTER S/N GAS:
481929307 ELECTRIC: 481929290)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove TOP FRONT COVER and BOTTOM
FRONT COVER.
2. Disconnect leads (1, Fig. 32) to door switch.
Fig. 32
3. Remove door switch bracket mounting screws
(2, Fig. 32).
4. Reverse the procedure to install new switch.
5. Perform DOOR SWITCH ADJUSTMENT.
6. Verify proper oven operation.
Page 17 of 50 F24575 Rev. A (0619)
Page 18
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
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 and follow Arc Flash procedures.
If test points are not easily accessible, disconnect power and follow Lockout/Tagout
procedures, attach test equipment and reapply power to test.
TEMPERATURE PROBE TEST (ALL
MODELS)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove the Right Side Panel as outlined under
"COVERS AND PANELS".
2. Remove the probe lead wires from the electronic
control.
3. Test the probe with an ohmmeter.
TEMPERATURE in °F RESISTANCE in Ω ±10%
77 90000
240 4077
260 3016
280 3266
300 1726
320 1332
340 1041
360 822
380 656
400 529
425 424
450 334
475 266
VERIFICATION OF SPARK AT
SPARK PROBE
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
1. Remove the Right Side Panel and Control
Panel as outlined under “COVERS AND
PANELS”.
2. Disconnect the high voltage lead from the
electrode.
DO NOT HOLD THE WIRE WITH YOUR HANDS
FOR THIS TEST. THE MANUAL GAS VALVE MUST
BE CLOSED
3. Clamp the wire in such a manner that the end of
the wire is 3/16" from the frame of the oven.
NOTE: It is critical that the wire be held 3/16" away
from the oven or sparking may not occur even though
the probe circuits are functioning properly.
F24575 Rev. A (0619) Page 18 of 50
Page 19
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
Fig. 33
THE FOLLOWING STEPS REQUIRE POWER TO
BE APPLIED TO THE UNIT DURING THE TEST.
USE EXTREME CAUTION AT ALL TIMES.
4. Plug the unit in and set the temperature controller
to the maximum setting.
4. Set the temperature control to the highest setting
and turn the power switch on. The burner must
be lit while adjusting the pressure.
5. Turn the adjustment screw to obtain the proper
gas pressure.
5. Turn the power switch on.
6. Sparking should occur after a 15 second purge
time. Arcing from the lead wire to the oven frame
should be observed at this time.
GAS PRESSURE ADJUSTMENT
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Shut off the gas before servicing the
unit and follow lockout / tagout
procedures.
1. Remove the Right Side Panel and Control
Panel as outlined under “COVERS AND
PANELS”.
2. Remove the plug from the test port and install the
manometer.
THE FOLLOWING STEPS REQUIRE POWER TO
BE APPLIED TO THE UNIT DURING THE TEST.
USE EXTREME CAUTION AT ALL TIMES.
Fig. 34
• Turn screw clockwise to increase pressure.
• Turn screw counterclockwise to decrease
pressure.
GAS TYPE
Natural 3.5 inches W.C.
Propane 10 inches W.C.
NOTE: If input pressure is below 4.0 (Natural) or 10.5
(Propane) inches W.C., the desired output cannot be
obtained and the oven will overate at a lower BTU.
SETTING AT OUTPUT
OF GAS VALVE
SPARK IGNITION CONTROL TEST
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
NOTE: Verify that the ground terminal is connected
to the oven ground.
3. Plug in the unit and turn on the gas.
Page 19 of 50 F24575 Rev. A (0619)
Page 20
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
No gas ignition & no sparking
1. Remove the Right Side Panel as outlined under
“COVERS AND PANELS”.
2. Plug in the unit and set the temperature controller
to 350°.
3. Turn the power switch on.
4. Check for 24 VAC between the power terminal
and ground terminal.
A. If 24 VAC is present, replace the spark
ignition control.
B. If 24 VAC is not present, check the
transformer, temperature controller, and
switches.
No gas ignition & no sparking
1. Remove the Right Side Panel as outlined under
“COVERS AND PANELS”.
2. Plug in the unit and set the temperature controller
to 350°.
3. Turn the power switch on.
2. Place a thermocouple in the geometric center of
the oven cavity.
NOTE: Oven temperature must be below 450°F.
NOTE: If oven is equipped with "Cook and Hold"
option, set to Cook (normal cooking) before
continuing.
3. Set the temperature control to the maximum
setting.
4. Check machine data plate for correct voltage to
oven. Refer to diagram below for proper terminal
locations and voltages before checking the
control. Use the correct terminals for the
corresponding voltage.
5. Turn the power switch to ON.
4. Check for 24 VAC between the power terminal
and ground terminal. The voltage should be
present after the 15 second purge and during the
10 second ignition period.
A. If 24 VAC is present, replace the spark
ignition control.
B. If 24 VAC is not present, check the
transformer, temperature controller, and
switches.
SOLID STATE CONTROL TEST
Certain procedures in this section
require electrical test or
measurements while power is
applied to the machine. Exercise
extreme caution at all times and
follow Arc Flash procedures. If test
points are not easily accessible,
disconnect power and follow
Lockout/Tagout procedures, attach
test equipment and reapply power to
test.
1. Remove the RIGHT SIDE PANEL.
Fig. 35
6. Check for proper voltage across terminals COM
AC to 120VAC or COM AC to 208-240VAC for
power to the control.
A. If correct, proceed to step 7.
B. If incorrect, problem is not with the
temperature control. See
TROUBLESHOOTING.
7. Check relay voltages on the board:
A. For 120VAC controls - check across
OUTPUT RELAY terminal (left side) to 120
VAC terminal for input to the internal relay.
Check across OUTPUT RELAY terminal
(right side) to 120 VAC for output from the
internal relay.
NOTE: If right side panel is not accessible, this
component can be serviced by removing CONTROL
PANEL.
F24575 Rev. A (0619) Page 20 of 50
Page 21
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
B. For 208-240VAC controls - check across
OUTPUT RELAY terminal (left side) to
208-240 VAC terminal for input to the
internal relay. Check across OUTPUT
RELAY terminal (right side) to 208-240 VAC
for output from the internal relay.
1) If input voltage to the internal relay is
correct, proceed to step 8. If input
voltage to the internal relay is not
present, problem is not with the
temperature control. See
TROUBLESHOOTING.
2) If output voltage from the internal relay
is correct proceed to step 8. If output
voltage from the internal relay is not
correct, check temperature probe as
outlined under TEMPERTURE
PROBE TEST (ALL MODELS).
8. Set the temperature control to the minimum
setting.
NOTE: Oven temperature must be above 300°F.
9. Check for zero (0) volts AC across terminals
OUTPUT RELAY terminal (right side) to 120 VAC
or OUTPUT RELAY terminal (right side) to
208-240 VAC for no output from the internal
relay.
A. If correct, temperature control is functioning
properly.
B. If incorrect, check temperature probe as
outlined under TEMPERTURE PROBE
TEST (ALL MODELS).
1) If temperature probe is OK:
a. Turn the power switch OFF.
3. Set the temperature control to 350 degrees F.
4. Allow the oven to cycle until the oven
temperature stabilizes. (cycle at least three
times)
5. Record the temperature at which the HEAT
LIGHT goes off and on.
A. Check for at least two complete heating
cycles.
6. Calculate the differential by subtracting the
temperature indicated when the heat light comes
on from the temperature indicated when the heat
light goes out.
Differential = Heat light OFF - Heat light ON.
Example: 360 (light out) - 340 (light on) = 20° F
differential.
A. The differential calculated should be less
than 20 degrees F.
1) If the differential is more than 20
degrees F, check temperature probe
and temperature control board as out
lined under "TEMPERATURE PROBE
TEST" and "SOLID STATE CONTROL
TEST".
7. Calculate the average temperature by adding the
temperature indicated when the heat light goes
out to the temperature indicated when the heat
light comes on and dividing this answer by 2.
[Temp.(light off)+ Temp.(light on)] ÷ 2 = Average
Temperature
Example:
360 + 340
2 2
8. If the average temperature differs more than 10
degrees F from the dial settings:
700
=
350°F average
temperature
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
b. Replace the temperature control
and check calibration as outlined
under SOLID STATE CONTROL
CALIBRATION.
SOLID STATE CONTROL
CALIBRATION
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the On-Off-Cool Down switch to ON.
Page 21 of 50 F24575 Rev. A (0619)
A. Pencil mark the knob pointer position as a
reference point on the control panel next to
the dial plate.
B. Remove the temperature control knob.
Page 22
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
DOOR SWITCH ADJUSTMENT (UP
TO S/N GAS: 481929306 ELECTRIC:
481929289)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove Top Front Cover.
NOTE: The door switch actuator should be operated
by the switch lever when the door is about ½" from
being closed.
2. Make adjustment if necessary.
Adjustment
Fig. 36
C. Loosen the two dial plate mounting screws
and the temperature control mounting nut.
Loosen only enough to turn the dial plate.
Fig. 37
D. Rotate the dial plate until the temperature
calculated in step 7 is in line with the pencil
mark.
A. Loosen the two switch mounting screws.
B. Adjust the switch bracket to obtain the
correct setting as outlined in step 2.
Fig. 38
C. Tighten the two switch bracket mounting
screws.
D. If the adjustment can not be obtained by
moving the switch, you can bend the tab of
actuator lever.
3. Install Top Front Cover.
DOOR SWITCH ADJUSTMENT
(AFTER S/N GAS: 481929307
ELECTRIC: 481929290)
E. If the above adjustment cannot be obtained,
check temperature probe and temperature
control board as outlined under "TESTING
TEMPERATURE CONTROL BOARD".
1. Remove BOTTOM COVER.
F24575 Rev. A (0619) Page 22 of 50
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
Page 23
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
NOTE: The door switch actuator should be operated
by the switch lever when the door is about ½" from
being closed.
2. Make adjustment if necessary.
Adjustment
A. Bend switch arm or acutator lever to adjust.
Fig. 39
3. Install BOTTOM COVER.
Fig. 40
4. Verify proper operation of door.
DOOR REVERSAL
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove the oven door.
A. Remove the door strike plate from the top of
the door.
B. Rotate the door 180°. The top of the door is
now the bottom.
C. Install the door strike on the new top of the
door. Use the screws removed to install the
strike plate to fill the holes on the bottom of
the door.
2. Remove the bottom door bushing and
antirotation plate.
Fig. 41
7. Remove the door switch from the switch
mounting bracket.
A. Use the other set of holes in the mounting
bracket to mount the switch.
Fig. 42
B. Place the switch insulation pad on the
mounting bracket.
3. Remove the knockout from the lower sill cover.
4. Install the plug button in the old door bushing hole
in the lower sill cover.
5. Install the bottom door bushing and anti-rotation
plate.
6. Remove the catch assembly from the oven.
A. Move the door catch to the opposite side of
the door catch channel.
B. Install the door catch assembly to the
opposite side of the top sill.
Page 23 of 50 F24575 Rev. A (0619)
Fig. 43
C. Install the switch onto the mounting bracket.
Page 24
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
Fig. 44
8. Install the door in the lower door bushing.
9. Install the top door bushing and door switch
mounting plate to the new position on the upper
sill.
10. Adjust the door as outlined under “DOOR
ADJUSTMENT”.
11. Adjust the door switch as outlined under “DOOR
SWITCH ADJUSTMENT”.
12. Replace the top front cover and check the oven
for proper operation.
C. Tighten the screws and install the top front
cover.
Fig. 46
DOOR ADJUSTMENT (AFTER S/N
GAS: 481929307 ELECTRIC:
481929290)
DOOR ADJUSTMENT (UP TO S/N
GAS: 481929306 ELECTRIC:
481929289)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. The door should be parallel with the face of the
oven cavity.
Fig. 45
2. If adjustment is needed:
A. Remove the top front cover as outlined
under “COVERS AND PANELS” in
“REMOVAL AND REPLACEMENT OF
PARTS”.
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove TOP FRONT COVER.
2. Loosen door mounting screws.
Fig. 47
3. Hold door to achieve parallel.
4. Tighten screws.
B. Loosen the screws that secure the door
support and move the door in the slot until it
is parallel with the face of the oven cavity.
F24575 Rev. A (0619) Page 24 of 50
Page 25
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
BLOWER ADJUSTMENT (UP TO S/
N GAS: 481929306 ELECTRIC:
481929289)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove rack and rack supports.
2. Remove baffle panel by lifting up and out.
3. Check the blower. It should be ¼” away from and
parallel to the oven wall. If not, proceed to step 4.
4. Remove the right side panel as outlined under
“COVERS AND PANELS”.
5. To adjust the blower at the sides (front and rear
of oven cavity), loosen the motor mounting bolts
and move the motor until the ¼” gap is obtained.
6. To adjust the blower at the top and bottom, place
shims between the motor mounting bracket and
the mounting base.
7. Reverse the procedure to install.
BLOWER ADJUSTMENT (AFTER S/
N GAS: 481929307 ELECTRIC:
481929290)
Disconnect the electrical power to
the machine and follow lockout /
tagout procedures.
1. Remove rack and rack supports.
2. Remove baffle panel by lifting up and out.
3. Check the blower. It should be ¼” away from and
parallel to the oven wall. If not, proceed to STEP
4.
4. Remove RIGHT SIDE PANEL.
5. Loosen blower mounting bolts.
6. Slide on motor shaft to get ¼” gap between
blower and fan cover.
7. Tighten blower mounting bolts.
8. Reverse the procedure to install.
Fig. 48
ELECTRONIC CONTROL
SPECIAL KEY FUNCTIONS - To activate these functions press the specified keys while turning the oven on. You
can not toggle between functions. Each function has to be entered from the off position.
NOTE: There are four hidden keys on the control. See diagram TSP1008C following the table.
HOLD KEYS 1 & 3 4 & 9 6 & 8
FUNCTION Calibration Mode Change between °C & °F Display test
Page 25 of 50 F24575 Rev. A (0619)
Page 26
HALF-SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
CALIBRATE OVEN - Perform Calibration at 350°F
1. Place a thermocouple near the geometric center
of the oven cavity.
2. Cycle oven until the cavity temperature
stabilizes. (usually 3 cycles)
3. Turn the oven off.
4. Enter the calibration mode.
5. Compare the set temperature to the measured
temperature.
6. Adjust the temperature on the display to match
the measured temperature.
7. Press key 3 to store the calibration information.
DISPLAY TEST - The control will cycle through a
continuous test until the oven is turned off. Each
segment of the displays will be lit in sequence, each
LED in order and then each digit will light.
Fig. 49
ERROR CODES
CODES CONDITIONS
E-01 High Limit Error - Check open probe.
E-02
E-03 Control compartment ambient temperature is above 215°F
E-04 Control compartment ambient temperature is below 32°F
Low Limit Error - check for 6 VAC from transformer. Check control pins 1-2 for 12 VAC
& pins 2-3.
HEATING ELEMENT TEST
Test each rod in the element assembly.
Values in the table are nominal (± 10%).
VOLTAGE WATTAGE AMPERAGE RESISTANCE
208 2500 12 17.33
240 2500 10.4 23.1
F24575 Rev. A (0619) Page 26 of 50
Page 27
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
ELECTRICAL OPERATION
COMPONENT FUNCTION
POWER SWITCH ..... Controls power to oven.
COOLDOWN
SWITCH ...............
FAN SPEED
SWITCH ...............
SOLID STATE
CONTROL ............
TIMER ................ Signals end of timed baking. Does not shut heater or burner off. (Solid state control)
ELECTRONIC
CONTROL ............
BLOWER MOTOR ..... Circulates air inside oven cavity. (Contains centrifugal switch for gas ovens) (2 speed
DOOR SWITCH ....... Allows heating of oven, only when the doors are closed.
TEMPERATURE
PROBE ...............
SOLID STATE
RELAY ................
TRANSFORMER ...... Provides 12 and 6 VAC power. (Electronic Control)
TRANSFORMER ...... Provides 24 VAC power to the spark ignition control if the centrifugal switch (part of blower
Prevents heaters from operating and allows fan to run. (On some solid state control
models, this switch is combined with the power switch)
Controls speed of oven cavity blower motor. (Electric ovens)
Controls oven temperature.
Controls oven temperature, cook and hold mode, pulse mode and time.
electric ovens)
Senses temperature of oven cavity for the solid state control and electronic control.
Controls power to blower motor. (Electronic Control)
motor) is closed. (Gas Ovens)
GAS VALVE .......... Allows gas to flow to burner. (Gas ovens)
SPARK MODULE ..... Generates spark for burner ignition, monitors flame, controls 15 second purge time and
10 second ignition time and power to gas valve. (Gas ovens)
POWER LIGHT ........ Lit whenever the power switch is ON. (Solid state control)
HEAT LIGHT .......... Lit whenever burner or heaters are operating. (Solid state control)
NO IGNITION
LIGHT .................
CONTACTOR ......... Powers heater elements. (Electric ovens)
FUSE ................. Protects control circuit. (Electric ovens)
Lit when sensor fails to detect flame. (Solid state control - Gas oven)
COMPONENT LOCATION
Page 27 of 50 F24575 Rev. A (0619)
Page 28
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
Fig. 50
Fig. 51
F24575 Rev. A (0619) Page 28 of 50
Page 29
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
SEQUENCE OF OPERATION - GAS
OVEN
IGNITION MODULE
1. 24VAC supplied to ignition module as described
under oven sequence of operation
A. 15 second prepurge period
1) No-ignition light is on
2) Cavity blower motor removes any
residual gas from combustion chamber
B. 10 second spark period
1) Gas valve energized
2) No-ignition light is off
2. The flame is monitored by a DC voltage of at least
5 microamps passing from the ignitor probe
through the flame to ground.
A. If the flame is detected before 10 seconds:
1) Sparking is terminated
2) Gas valve held open
3) Monitoring of flame continues
B. If a flame is not established after the 10
second spark period
1) A second 15 second prepurge period
2) A second 10 second spark period
C. If a flame is not established after the second
10 second spark period
1) A third 15 second prepurge period
2) A third 10 second spark period
D. If a flame is not established after the third 10
second spark period, the module will go into
lock out .
1) No ignition light on
3. To reset the ignition module perform one of the
following
A. Turn power switch off; then on
B. Open and close the door
C. Turn the temperature control all the way off
then back to the set temperature
4. If a flame is established then is extinguished
before the temperature control is satisfied, the no
ignition light will be on and the ignition module will
attempt to light the burner in the sequence
described above.
Solid State Control
1. Conditions
A. Supply voltage to unit
1) L1 to power/cooldown switch
2) N (120V) or L2 (220V) to motor; ignition
transformer; power light; heat light;
temp control (pin 9); buzzer; timer
motor
3) Good chassis ground for the ignition
system; no ignition light; gas valve;
control module transformer
B. Power/cooldown switch off
C. Oven at room temperature D. Temperature
control set to desired temperature
D. Manual gas valve open
E. Door switch closed
2. Power/cooldown switch turned "on"; L1 voltage
to:
A. Power light
B. Control pin 8 and pin 7
C. Blower motor energized; thru power switch,
door switch
D. Pin 1 of timer
E. Control calls for heat; contacts 6/7 closed
1) Heat light
2) Primary of 24 VAC ignition transformer
3. 24 VAC to contacts of blower motor centrifugal
switch
4. As blower motor reaches operating speed,
blower motor centrifugal switch closes A. 24 VAC
to ignition module
5. Ignition module operates (see ignition module
sequence of operation)
6. Temperature is satisfied and control contacts 6/7
open.
A. Heat light goes out.
B. Power removed from ignition transformer.
1) Gas valve shuts off gas supply to
burner.
7. Oven cycles on solid state control until power/
cooldown switch is moved from the "on" position
or the door is opened.
Page 29 of 50 F24575 Rev. A (0619)
Page 30
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
NOTE: The blower motor and gas valve (solenoid)
are de-energized when the door is opened while the
oven is in the heat mode.
Electronic Control
Preheat
1. Conditions. A. Supply voltage to unit. 1) L1 (black
120V) to power/cooldown switch 2) N (120V) or
L2 (220V) to motor; primary of ignition
transformer; primary of control transformer 3)
Good chassis ground for the ignition system;
electronic control; gas valve; ignition module
transformer B. Power/cooldown switch "off". C.
Oven at room temperature. D. Door switch
closed. E. Manual gas valve open.
2. Power/cooldown switch turned "on"; L1 voltage
to: A. Primary of control transformer 1) 6 VAC in at pin 3 of control 2) 12 VAC - in at pin 1 of
control 3) Common - in at pin 2 of control B.
Terminal 1 of solid state relay C. Pin 13 of control
3. Control set to desired temperature using set
knob.
A. 10 VDC output on pin 4 of control, thru door
switch to:
1) Power/cooldown switch
2) Pin 11 of control - This input at pin 11
signals the control that the door is
closed and the burner can be lit.
3) Terminal 3 of ss relay
B. Pin 15 of control to 24 volt transformer (L1
voltage) 1) 24 VAC to blower motor
centrifugal switch
C. Pin 10 of control to ss relay terminal 4
1)
1. Conditions A. Oven in preheat.
2. Temperature is set.
3. Time is set and start key pressed.
4. Oven cycles at set temperature.
NOTE: In pulse mode (initiated at the beginning of the
bake cycle), the blower motor is operated in 45 second
cycles, with the first cycle being off then 45 seconds
on. The pulse time cannot be longer than the bake
time.
5. Time expires.
A. Buzzer sounds continually until turned off.
6. Oven continues to cycle at set temperature.
NOTE: The blower motor and gas valve (solenoid)
are de-energized when the door is opened while the
oven is in the cook mode.
Cook and Hold
1. Conditions A. Oven in preheat.
2. A bake temperature and time is set.
3. A hold temperature and time is set and start key
pressed.
4. Oven cycles at set temperature.
NOTE: In pulse mode (initiated at the beginning of the
bake cycle), the blower motor is operated in 45 second
cycles, with the first cycle being off then 45 seconds
on. The pulse time cannot be longer than the bake
time.
5. Time expires in cook mode.
A. A. Buzzer sounds (short beep).
B. Control lowers temperature to hold
temperature.
4. Blower Solid state relay energizedmotor
energized.
5. As blower motor reaches operating speed,
blower motor centrifugal switch closes. A. 24
VAC to ignition module
6. Ignition module operates (see ignition module
sequence of operation)
7. Oven cycles on electronic control until power/
cooldown switch is moved from the "on" position,
a different mode is selected or the door is
opened.
NOTE: The blower motor is de-energized and gas
valve (solenoid) closed when the door is opened while
the oven is in the heat mode.
Cook
F24575 Rev. A (0619) Page 30 of 50
6. Oven temperature reaches hold temperature.
7. Oven continues to cycle at hold temperature until
NOTE: The blower motor and gas valve (solenoid)
are de-energized when the door is opened while the
oven is in the hold mode.
Cooldown
1. Conditions
2. Power/cooldown switch to cooldown position.
3. Blower motor energized.
A. Display counts up time and flashes "hold"
oven is turned off or the hold function is turned
off.
A. Cooking completed, oven temperature
needs to be lowered.
Page 31
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
A. Door switch does not affect operation.
B. Burner will not lite.
4. Oven operates until power switch is moved from
cooldown position.
SEQUENCE OF OPERATION -
ELECTRIC OVEN
Solid State Control
1. Conditions.
A. Fuses are good.
B. Supply voltage to unit.
1) L1 to power switch and one side of
heater contacts C1, C2, C3
2) L2 (L3 three phase) to motor; contactor
coil; power light; heat light; temp
control (pin 9); buzzer; timer motor; one
side of heater contacts C2, C3 (C3 only
for three phase)
NOTE: L2 of three phase connection goes to one side
of heater contacts C2 3)
3) Good chassis ground
C. Power switch "off"
D. Oven at room temperature
E. Solid state control set to desired
temperature.
F. Door switch closed
G. Fan speed switch in either position
2. Power switch turned "on", L1 voltage to:
A. A. Power light
B. Control pins 7 & 8
C. Blower motor energized
D. Pin 1 of timer
3. Control calls for heat, contacts 6/7 closed.
A. Contactor coil energized.
1) Heating elements energized.
B. Heat light is on.
4. Oven reaches set temperature and control
contacts 6/7 open.
A. Power removed from contactor coil.
1) Heating elements de-energized.
B. Heat light goes out.
5. Oven cycles on solid state control until power
switch is moved from the "on" position or the door
is opened.
NOTE: The blower motor is de-energized when the
door is opened and the oven is in the heat mode.
Electronic Control
Preheat
1. Conditions. A. Fuses are good. B. Supply voltage
to unit. 1) L1 to power switch and one side of
heater contacts C1 2) L2 (L3 three phase) to
motor; contactor coil; power light; heat light; temp
control (pin 9); buzzer; timer motor; one side of
heater contacts C2, C3 (C3 only for three phase)
NOTE: L2 of three phase connection goes to one
side of heater contacts C2 3) Good chassis
ground B. Power switch "off" C. Oven at room
temperature D. Door switch closed E. Fan speed
switch in either position
2. Power/cooldown switch turned "on"; L1 voltage
to: A. Primary of control transformer 1) 6 VAC in at pin 3 of control 2) 12 VAC - in at pin 1 of
control 3) Common - in at pin 2 of control B.
Terminal 1 of solid state relay contacts C. Pin 13
of control
3. Control set to desired temperature using set
knob.
A. 10 VDC output on pin 4 of control, thru door
switch to:
1) Power/cooldown switch
2) Pin 11 of control - This input at pin 11
signals the control that the door is
closed and the oven can heat.
3) Terminal 3 of ss relay
B. Pin 15 of control to contactor coil (L1
voltage)
1) Heaters energized
C. Pin 10 of control to ss relay terminal 4
1) Solid state relay energized
4. Blower motor energized
5. Oven reaches set temperature:
A. Power removed from contactor coil
1) Heating elements de-energized
6. Oven cycles on electronic control until power
switch is moved from the "on" position or the door
is opened.
NOTE: The blower motor is de-energized when the
door is opened and the oven is in the heat mode.
Page 31 of 50 F24575 Rev. A (0619)
Page 32
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
Cook
1. Conditions
A. Oven in preheat.
2. Temperature is set.
3. Time is set and start key pressed.
4. Oven cycles at set temperature.
NOTE: In pulse mode (initiated at the beginning of the
bake cycle), the blower motor is operated in 45 second
cycles, with the first cycle being off then 45 seconds
on. The pulse time cannot be longer than the bake
time.
5. Time expires.
A. Buzzer sounds continually.
6. Oven continues to cycle at set temperature.
NOTE: The blower motor is de-energized when the
door is opened and the oven is in the cook mode.
Cook and Hold
1. Conditions
A. Buzzer sounds (short beep).
B. Control lowers temperature to hold
temperature.
6. Oven temperature reaches hold temperature.
A. Display counts up time and flashes "hold"
7. Oven continues to cycle at hold temperature until
oven is turned off or the hold function is turned
off.
NOTE: The blower motor is de-energized when the
door is opened and the oven is in the hold mode.
Cooldown
1. Conditions
A. Cooking completed, oven temperature
needs to be lowered.
2. Power/cooldown switch to cooldown position.
3. Blower motor energized.
A. Door switch does not affect operation.
B. The heaters will not energize.
A. Oven in preheat.
2. A bake temperature and time is set.
3. A hold temperature and time is set and start key
pressed.
4. Oven cycles at set temperature.
NOTE:
5. Time expirIn pulse mode (initiated at the
beginning of the bake cycle), the blower motor is
operated in 45 second cycles, with the first cycle
being off then 45 seconds on. The pulse time
cannot be longer than the bake time.es in cook
mode.
4. Oven operates until power switch is moved from
cooldown position.
F24575 Rev. A (0619) Page 32 of 50
Page 33
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
SCHEMATICS GAS OVENS
HGC20 - UP TO S/N: 481929306
Page 33 of 50 F24575 Rev. A (0619)
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HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
AFTER S/N: 481929307
F24575 Rev. A (0619) Page 34 of 50
Page 35
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HG20D
Page 35 of 50 F24575 Rev. A (0619)
Page 36
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
WIRING DIAGRAM - GAS OVENS
HGC20 - Control Section - UP TO S/N: 481929306
F24575 Rev. A (0619) Page 36 of 50
Page 37
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HGC20 - Oven Section - UP TO S/N: 481929306
Page 37 of 50 F24575 Rev. A (0619)
Page 38
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
AFTER S/N: 481929307
F24575 Rev. A (0619) Page 38 of 50
Page 39
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HGC20D - Control Section
Page 39 of 50 F24575 Rev. A (0619)
Page 40
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HGC20D- Oven Section
F24575 Rev. A (0619) Page 40 of 50
Page 41
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
SCHEMATICS - ELECTRIC OVENS
HEC20 - UP TO S/N: 481929289
Page 41 of 50 F24575 Rev. A (0619)
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HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
AFTER S/N: 481929290
F24575 Rev. A (0619) Page 42 of 50
Page 43
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HEC20D
Page 43 of 50 F24575 Rev. A (0619)
Page 44
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
WIRING DIAGRAM - ELECTRIC OVENS
HEC20 - Control Section - UP TO S/N: 481929290
F24575 Rev. A (0619) Page 44 of 50
Page 45
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HEC20 - Oven Section - UP TO S/N: 481929289
Page 45 of 50 F24575 Rev. A (0619)
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HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
AFTER S/N: 481929290
F24575 Rev. A (0619) Page 46 of 50
Page 47
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HEC20D - Control Section
Page 47 of 50 F24575 Rev. A (0619)
Page 48
HALF-SIZE CONVECTION OVENS - ELECTRICAL OPERATION
HGC20D- Oven Section
F24575 Rev. A (0619) Page 48 of 50
Page 49
HALF-SIZE CONVECTION OVENS - TROUBLESHOOTING
TROUBLESHOOTING
ELECTRIC OVENS
SYMPTOM POSSIBBLE CAUSED
1. Main breaker open.
No power to oven controls.
No oven operation; power to controls. 1. Power/cooldown switch inoperative.
Blower motor operates when oven is heating, but not in
cooldown.
Blower motor does not operate, oven heats.
Oven is slow to heat or not hot enough.
2. Control circuit fuses open.
3. 12/6 volt transformer inoperative. (Electronic
control)
1. Power/cooldown switch inoperative.
1. Door switch open or inoperative.
2. Speed selection switch malfunction.
3. Blower motor inoperative.
4. Solid state relay malfunction. (Electronic Control)
5. Electronic control inoperative. (Electronic Control)
1. Incorrect line voltage.
2. One phase of 3 phase out.
3. Thermostat or control malfunction.
4. Blower motor inoperative.
5. Contactor malfunction.
6. Temperature probe malfunction.
1. Thermostat or control not calibrated.
Oven temperature is too hot.
No heat; blower motor operates.
Electronic control does not function.
Door does not seal or will not shut properly.
2. Thermostat or control malfunction.
3. Contactor inoperative.
1. Thermostat or control not calibrated.
2. Thermostat or control malfunction.
3. Contactor inoperative.
1. See "ELECTRONIC CONTROL" in "SERVICE
PROCEDURES AND ADJUSTMENTS".
1. Doors out of adjustment.
2. Door seals inoperative.
3. Door catch malfunction.
GAS OVENS
Page 49 of 50 F24575 Rev. A (0619)
Page 50
HALF-SIZE CONVECTION OVENS - TROUBLESHOOTING
SYMPTOM POSSIBBLE CAUSED
1. Unit unplugged
No power to oven controls.
No oven operation; power to controls.
Gas does not ignite; no spark.
Oven is slow to heat or not hot enough.
2. Power/cooldown switch inoperative.
3. 12/6 volt transformer inoperative. (Electronic
control)
1. Door switch open or inoperative.
2. Solid state relay malfunction. (Electronic control)
3. Blower motor malfunction.
4. Electronic control malfunction.
1. 24 volt transformer not functioning.
2. Spark ignition control inoperative or not grounded.
3. Solid state control or probe malfunction.
4. Electronic control or probe inoperative.
5. Centrifugal switch in blower motor inoperative.
1. Gas pressure not correct.
2. Control malfunction.(solid state or electronic)
3. Probe inoperative.
4. Blower motor malfunction.
5. Check orifice.
1. Insufficient gas pressure.
Gas ignites, but will not maintain flame.
Sparks but does not ignite.
Electronic control does not function.
Door does not seal or will not shut properly.
2. Flame sensor not positioned in flame.
3. Spark ignition control malfunction.
4. Check orifice.
1. Manual gas valve off.
2. Gas valve (solenoid) malfunction.
3. Spark ignition control inoperative.
1. See "ELECTRONIC CONTROL" in "SERVICE
PROCEDURES AND ADJUSTMENTS".
1. Doors out of adjustment.
2. Door seals inoperative.
3. Door catch malfunction.
F24575 Rev. A (0619) Page 50 of 50
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