Bunn Axiom Series Technical Training Manual page 26

Temperature Probe
The temperature probe is inserted through the tank lid assembly.
Test Procedures:
1. Connect the brewer to the power source.
2. With a DC voltmeter, check voltage across the two wires at J9 on control
board (Blackprobe to black wire, red probe to white wire. The indication should
be aproximately between 4vdc cool to 1vdc at ready temperature.
3. Disconnect the brewer from the power source.
• If voltage is present as described, circuit is working correctly, check high
limit thermostat (and TCO on 230V models).
• If voltage is not present as described, proceed to #4.
4. Disconnect temperature probe from J9 on control board. Check the
resistance across the two terminals of the temperature probe. The indication should be approximately between 10.5K
cool to 870 at ready temperature.
• If resistance is to specification, replace the control board.
• If resistance is not to specification, replace the temperature probe.
High Limit Thermostat
The limit thermostat is located inside the top cover on the front side of the
tank.
Test Procedures:
1. Disconnect the brewer from the power source.
2. Disconnect the wires from the limit thermostat.
3. With an ohmmeter, check for continuity across the limit thermostat
terminals.
• If continuity is present as described, the limit thermostat is operating
properly.
• If continuity is not present as described, replace the limit thermostat.
Refill Valve
The refill valve is located inside the front of the brewer.
Test Procedures:
1. Enter programming level 2, scroll to "Service Tools" then scroll to "Refill Valve".
2. Briefly activate the refill valve in the test mode. With a voltmeter, check the voltage across the coil wires.
3. The indication must be 120 volts ac for two wire 120 volt models and three wire 120/208 -240 volt models or 230
volts ac for two wire 230 volt models.
• If voltage is present, proceed to # 4.
• If voltage is not present, refer to Wiring Diagrams and check main
wiring harness. If harness checks ok, replace control board.
4. Check the refill valve for coil action. Briefly activate the refill valve in the
test mode and listen carefully near the refill valve for a "clicking" sound as
the magnetic coil pulls the plunger in.
• If the sound is heard as described and water will not pass through the
refill valve, there may be a blockage in the water line before the refill
valve or, the solenoid valve may require inspection for wear, and
removal of waterborne particles.
• If the sound is not heard as described, proceed to # 5.
5. Disconnect the brewer from the power source.
6. Check for continuity across the refill valve coil terminals.
• If continuity is not present as described, replace the refill valve.
• If continuity is present as described, there could be some debris in the valve.
26
AXIOM Training Manual
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Flow Control Body
Flow Control Washer
Strainer