9
MAINTENANCE and TROUBLESHOOTING CONT’D
PERFORMANCE AND INSPECTION
A periodic check of thermostat calibration should be performed. To check oven calibration attach a thermocouple to
the mid-point of the thermostat bulb in the oven cavity. Turn the temperature dial to 350°F and turn the oven ON. Wait
approximately 20 minutes until the oven temperature has stabilized. If the average of the ON and OFF thermostat
readings is within 10°F of 350°F the oven is in calibration. If not, remove the temperature knob and turn the small
screw in the middle until oven is in calibration. Replace the knob and the oven is ready for normal operation.
MAJOR COMPONENT DISASSEMBLY, REPAIR, REPLACEMENT & REASSEMBLY
(Refer to figure #4, page 22)
THERMOSTAT, CONTACTORS (RELAYS), SWITCHES
These parts are located behind the control panel assembly on the right hand side of each oven. Remove the screws
attaching the control panel to the front of the oven. Slowly pull out the control panel until the component requiring
replacement is accessible.
THERMOSTAT REPLACEMENT:
Inside the oven cavity remove the retaining clips holding the thermostat-sensing bulb in place. Feed the bulb through
the oven wall into the control panel area. Remove the wires attached to the thermostat terminals. Remember the
terminal each wire was on and attach the wires to the same terminal on the new thermostat. Remove the screws
holding the old thermostat to the front of the control panel. Discard old thermostat. Mount the new thermostat to
the control panel, carefully feed the sensing bulb through the oven wall, and reattach the sensing bulb to the oven
side using the retaining clips removed earlier. Close control compartment. Restore power to oven. Refer to the
“Performance and Inspection” section to verify proper operation of the new thermostat.
ELEMENT REPLACEMENT:
The element is located inside the oven cavity. To replace the element, remove the baffle at the back of the oven.
This will expose the elements to plain view and allow easy access. Remove the element mounting screws located
near the top of the oven. Gently, pull the element into the oven cavity. There is enough wire connected to the
element to allow easy access to the terminals located behind the element mounting plate. Move each wore from the
existing terminal to the corresponding terminal on the new element.
DO NOT
mix up these wires! After all wires are
transferred to the new element, feed the wire back through the access hole in the back of the oven and attach the
element to the oven wall with the screws removed earlier. Replace the baffle. Refer to the “Initial Start-up” section
to restore the oven to proper operation.
CONTACTOR (RELAY), SWITCH REPLACEMENT:
Pull out control panel as previously outlined. Remove the wires from the contactor or switch being changed. Place
those wires on the corresponding terminal of the new part. Remove old part and mount new part with wires attached
in the spot where the old part used to be. Reinstall the control panel, restore power to the oven. Turn oven on, set
thermostat to 200°F and allow oven to cycle 3 times or until the technician is satisfied with the proper operation of
the oven.
BLOWER WHEEL REPLACEMENT:
The blower wheel is located inside the oven cavity. To replace the blower wheel, remove the baffle at the back of
the oven. This will expose the blower wheel to plain view and allow easy access. Loosen the two (2) set screws
holding the blower wheel onto the motor shaft. Using a three-finger blower wheel puller, grasp the puller ring with
all three fingers and tighten the puller until the blower wheel hub clears the motor shaft. Place new blower wheel
on the motor shaft and position exactly 5/8” from the oven back motor plate. Tighten the set screw positioned over
the flat on the motor shaft. Spin the fan to make sure it spins straight. Tighten the second set screw and re-tighten
the first set screw. Replace the baffle. The oven is now ready to re-start.
