Control Thermostat - Bunn VPR-VPSSERIES Service & Repair Manual

SERVICE (cont.)

CONTROL THERMOSTAT

FIG. 8-1 CONTROL THERMOSTAT
Location:
The control thermostat is located inside the
hood.
Test Procedures:
1. Disconnect the brewer from the power source.
2. Locate the black wire on the control thermo-
stat.
3. Check the voltage across the black wire on the
control thermostat and the white wire on the
tank heater or the red wire on the tank heater
with a voltmeter. Plug-in the brewer to the power
source. The indication must be:
a) 120 volts ac for two wire 120 volt models.
b) 220 volts ac for two wire 220 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 the brewer wiring harness.
5. Locate the blue/black wire on the control ther-
mostat.
6. Gently remove the capillary bulb and grommet
from the tank.
7. Check the voltage across the blue/black wire of
the control thermostat and the white wire on the
tank heater or red wire on the tank heater with a
voltmeter when the control thermostat is turned
"ON" (fully clockwise). Plug-in the brewer to the
power source. The indication must be:
a) 120 volts ac for two wire 120 volt models.
b) 220 volts ac for two wire 220 volt models.
Voltage must not be present across these terminals
when the thermostat is turned "OFF" (fully counter-
clockwise).
8. Disconnect the brewer from the power source.
If voltage is present as described, reinstall the capillary
tube into the tank to the line 4.5" above the bulb, the
control thermostat is operating properly.
If voltage is not present as described, replace the
thermostat.
Alternate Test Procedure:
1. Disconnect the brewer from the power source.
2. Remove leads from control thermostat termi-
nals.
3. Gently remove the capillary bulb and grommet
from the tank.
4. Check for continuity across the control thermostat
terminals. The indication must be:
a) Continuity "ON" (fully clockwise).
b) No continuity "OFF" (fully counterclockwise).
If continuity is not as described, replace the thermo-
stat.
FIG. 8-2 CONTROL THERMOSTAT TERMINALS
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