MN-28871 • Rev 5 • 10/17 • 750-CTUS Hot Food Holding Cabinet 17
Service
Thermostat and Indicator Light
Whenever the thermostat is turned “ON,” the indicator
light will indicate the power ON/OFF condition of the
heating cable, and consequently, the cycling of the cabinet
as it maintains the dialed cavity temperature. If this
light does not illuminate after normal start-up, the main
power source, thermostat, and/or indicator light must be
checked.
If the warming cabinet does not hold the temperature
as dialed, the calibration of the thermostat must be
checked. If the warming cabinet fails to heat or heats
continuously with the thermostat “OFF,” the thermostat
must be initially checked for proper operation. If these
items are checked and found to be in order, a continuity
and resistance check of the heating cable should be made.
SEE CIRCUIT DIAGRAM.
Thermostat Calibration
The thermostat is precision calibrated at the factory.
Normally, no adjustment or recalibration is necessary
unless the thermostat has been mishandled in transit,
changed or abused while in service. A thermostat
with a sensing bulb operates on hydraulic pressure,
consequently, any bending of the bulb results in a change
in its volume, and alters the accuracy of the thermostat
calibration.
A thermostat should be checked or recalibrated by placing
a quality, thermal indicator at the center of an empty
holding cavity. Do not calibrate with any food product
in the cabinet.
The thermostat should be set, and should
be allowed to stabilize at that setting for a minimum
of one hour. The center of the thermal swing of the air
temperature within the cabinet should approximately
coincide with the thermostat setting.
If calibration is necessary, the calibration screw should
be adjusted with great care. The calibration screw of
the thermostat is located in the thermostat dial shaft.
With the shaft held stationary, a minute, clockwise
motion of the calibration screw appreciably lowers the
thermostat setting. A reverse, or counter-clockwise motion
appreciably raises the thermostat setting. After achieving
the desired cycling of the thermostat, the calibration
screw must be sealed. Place a few drops of enamel sealant
directly on the calibration screw.
(Red nail polish or equivalent is acceptable.)
This section is provided for the assistance of
qualified and trained service technicians only
and is not intended for use by untrained or
unauthorized service personnel. Failure to
observe this precaution may void the warranty.
Cable Heating Service Kit No. 4881
Kit includes:
BU-3106
Cup Bushing
12
CB-3045
Cable Heating Element
210 feet ST-2439
Stud
12
CR-3226
Ring Connector
12
NU-2215
Hex Nut
24
IN-3488
Insulation Corner
1 foot
SL-3063
Insulating Sleeve
12
BU-3105
Shoulder Bushing
12
TA-3540
Electrical Tape
1 roll
