Control Thermostat - Bunn Dual Service Manual

SERVICE (cont.)

CONTROL THERMOSTAT

Location:
The control thermostat is located inside the lower
left front of the brewer on the component bracket.
1. Disconnect the brewer from the power source.
2. Locate the blue wire on the control thermostat.
3. With a voltmeter, check the voltage across the
blue wire on the control thermostat and the white
insert on the two or three pole 120V, 120/208V,
120/240V terminal block and the red insert on
two pole 200V, 240V terminal block. Connect the
brewer to the power source. The indication must
be:
a.) 120 volts ac for two wire 120V models, three
wire 120/208 volt models and three wire 120/240
volt models.
b.) 200 to 240 volts ac for two wire 200 or 240
volt models.
4. Disconnect the brewer from the power source.
If voltage is present as described, proceed to #5.
If voltage is not present as described, refer to the Wiring
Diagrams and check brewer wiring harness.
FIG. 9 CONTROL THERMOSTAT
ga l
1 1⁄2
1 ga l
ga l
1⁄2
D Y
R EA
R
C TO
LE
SE
M ER
AR
/ W
O N
T
AR
ST
l
1⁄2 ga
l 1
1 ga
l
1⁄2 ga
T
AR
ST
M ER
AR
/ W
O N
R
C TO
LE
SE
D Y
R EA
ER
AT
T W
HO
N
IO
UT
CA
!
P779
5. Locate the black wires from the control thermo-
stat.
6. Gently remove the capillary bulb and grommet
from the tank.
7. With a voltmeter, check the voltage across the
black wires of the control thermostat and the white
insert on the two pole or three pole 120V, 120/208V,
120/240V terminal blocks and the red insert on two
pole 200V, 240V terminal blocks when the control
thermostat is turned "ON" (fully clockwise). Connect
the brewer to the power source. The indication
must be:
a.) 120 volts ac for two wire 120V models, three
wire 120/208 volt models and three wire 120/240
volt models.
b.) 200 to 240 volts ac for two wire 200 or 240
volt models.
Voltage must not be indicated across these ter-
minals when the thermostat is turned "OFF" (fully
counterclockwise).
8. Disconnect the brewer from the power source.
If voltage is present as described, reinstall the capillary
tube into the tank to the line 7" above the bulb, the
control thermostat is operating properly.
If voltage is not present as described, replace the
thermostat.
Removal and Replacement:
1. Remove wires from the control thermostat.
2. Remove the thermostat capillary bulb by firmly
pulling up on the capillary tube at the tank lid. This
will disengage the grommet from the tank lid.
3. Remove the #8-32 slotted head screw holding the
control thermostat to the component bracket.
4. Slide the grommet to the line 7" above the bulb on
the new capillary tube.
5. Insert the capillary bulb through the hole in the
tank lid and press the grommet firmly and evenly
so that the groove in the grommet fits into the tank
lid.
6. Carefully bend the capillary tube so that the tube
and bulb inside the tank are in the vertical posi-
tion.
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