Service manual

PG. 8 #825/33/37 INSTALLATION/OPERATION/SERVICE MANUAL
THERMOSTAT/PILOT LIGHT SEQUENCE
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 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.
Following temperature stabilization, 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.)
SERVICE