Left & Right Cooling Drum Temperature Sensor - Bunn Ultra NX Service & Repair Manual

Left and Right Cooling Drum Temperature Sensor
FIG. 19 TEMPERATURE SENSOR
Location:
The Cooling Drum Temperature Sensor(s) are
located inside the top rear of the cooling drum
housing behind the Auger Motor cover.
Rear Cover Removal:
1. Remove 4 screws securing rear cover.
2. Grab cover and pull away from machine.
Test Procedures:
NOTE: Each cooling drum real time temperature
can be viewed by accessing the program real time
status menu by simultaneously pressing and
holding Left & Right Dot for 5 seconds to display
the TEMP & TORQUE screen. The temperature of
each cooling drum and the hot gas temperature
can be seen.
Voltage Check
1. Connect a voltmeter, across the two leads of
the temperature sensor (leave plug connected);
The indication must be:
a) Approximately. 2.6 vdc @ 32° F
b) Approximately. 1.4 vdc @ 71° F
If voltage reading is 0v, the Control Board is not
supplying the necessary 5v and should be
replaced. If the reading stays at 5vdc, replace
thermistor.
SERVICE - REAR COVER COMPONENTS
Resistance Check
2. Disconnect the plug on thermistor leads and
check resistance as indicated below.
The indication must be within range of known
temperature:
a) 1,473 - 1,614 ohms @ 32° F
(Water with Ice)
b) 394 - 454 ohms @ 71° F
(Room Temperature)
If resistance reading is not within the range
listed above, replace thermistor.
Part Removal and Replacement:
1. Disconnect the dispenser from the power
source.
2. Locate the temperature sensor 2-pin connector,
push-in the connector tab to release temperature
sensor connector from the machine wiring
harness.
3. Pull the insulating pipe cork tape away from the
temperature sensor.
4. Grab temperature sensor wires and begin
gently pulling temperature senor out of housing.
See FIG. 19.
5. Install replacement temperature senor into
housing and push the sensor all the way until it
stops (approximately 10.50 inches).
6. Reconnect temperature sensor 2-pin connector
to machine wiring harness.
7. Reseal insulating pipe cork tape around the
inlet and temperature sensor wires to seal and
hold sensor in position.
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