BUNN - AXIOM SERIES _ BREWER _ Service Help _ Contn - 4 of 5.

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                                                                   4 OF 5

LIMIT THERMOSTAT

• The limit thermostat is located inside the top cover on the front side of the tank.

TEST PROCEDURE

• Disconnect the brewer from the power source.
• Disconnect the wires from the limit thermostat.
• 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.

REMOVAL & REPLACEMENT

• Remove the wires from limit thermostat terminals.
• Carefully slide the limit thermostat out from under the retaining clip and remove limit thermostat.
• Carefully slide the new limit thermostat into the retaining clip. Ensure the metal face has good contact with tank

TCO CHECK

• The TCO's are located under the tank at the heater  connections.

TEST

Thermal cutoff  [For 230V Models only]

• Disconnect the brewer from the power source.
• Disconnect the TCO from the tank heater.
• With an ohmmeter, check for continuity across the TCO as shown above.
• If continuity is not present as described, replace the main harness.

BLANKET WARMER

• The blanket warmer is wrapped around the tank assembly

OPRATION

• The blanket warmer provides a low consistent heat around the tank at the point of the temperature sensor. This additional heat aids the heater circuit by reducing the number of on/off cycles, thereby extending the life of the relay contacts and the heater.

TEST

• Disconnect the brewer from the power source.
• With a voltmeter, check voltage across the two wires at the warmer element with the "ON/OFF" switch in the "ON" position. Connect the brewer to the power source. The indication must be 120 volts ac for two wire 120 volt models and three wire 120/208 and 120/240 volt models, or 230 volts ac for two wire 230 volt models.
• Disconnect the brewer from the power source.
• If voltage is present as described, proceed to *4.  If voltage is not present as described, refer to Wiring Diagrams and check wiring harness.
• Check the resistance across the two terminals on the blanket warmer. Refer to chart below.
• If resistance is to specifi cation, reconnect the two wires to the blanket warmer.  If resistance is not to specifi cation, replace the blanket Warmer.

50W-120V > 288.0 OHMS

50W-220V > 969.0 OHMS

REMOVAL & REPLACEMENT

• Disconnect the blanket warmer wire from the piggyback terminal on the refill valve.
• Remove the tank assembly from the brewer.
• Peel old blanket warmer off tank.
• Install new blanket warmer on tank with bottom of blanket 1½˝ from bottom of tank.
• Connect one of the white wires to the piggyback terminal on the limit thermostat.
• Reinstall tank assembly.
• Connect the other white wire to the piggyback terminal on the refill valve.

TEMPERATURE PROBE

• The temperature probe is inserted through the tank lid assembly.

TEST

• Disconnect the brewer from the power source.
• With a DC voltmeter, check voltage across the two wires at J9 on control board (Black probe to black wire, red probe to white wire.  Connect the brewer to the power source.  The indication should be between 4vdc cool to 1vdc at ready temperature.
• Disconnect the brewer from the power source.
• If voltage is present as described, circuit is working correctly, check limit thermostat (and TCO on 230V models).

If voltage is not present as described:

• Disconnect temperature probe from J9 on control board. Check the resistance across the two terminals of the temperature probe. The indication should be between 10.5K cool to 870 at ready temperature.

WARMER ELEMENTS

• The warmer element(s) is located under the warmer plate.

TEST

• Disconnect the brewer from the power source.
• With a voltmeter, check voltage across the two wires at the warmer element with the "ON/OFF" switch in the "ON" position. Connect the brewer to the power source. The indication must be 120 volts ac for two wire 120 volt models and three wire 120/208 and 120/240 volt models, or 230 volts ac for two wire 230 volt models.
• Disconnect the brewer from the power source.

If voltage is present as described, proceed:

• Check the resistance across the two terminals on the warmer element.

If resistance is to specification, reconnect the two wires to the warmer element.

If resistance is not to specification, replace the warmer element.

WARMER	RESISTANCE IN OHMS
100W-120V	144.0
100W-220V	484.0
100W-200V	400.0
TERMINAL TO SHEATH	INFINITE [OPEN]

REMOVAL & REPLACEMENT

• Remove the three *4-40 screws securing the warmer assembly to the brewer.
• Lift the warmer assembly from the brewer.
• Disconnect the two wires from the warmer element terminals.
• Remove the two *8-32 nuts securing the warmer element to the warmer plate.
• Securely install new warmer element.
• Reconnect the two wires to warmer element terminals.
• Securely install warmer assembly on the brewer

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