Manuals / Bunn / Kitchen Appliance / Coffeemaker

Bunn U3A service manual TROUBLESHOOTING cont PROBLEM, Probable Cause, Remedy

Models: U3A U3

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TROUBLESHOOTING (cont.)

PROBLEM

Water not hot

Circuit breaker keeps tripping

Water keeps running from swing spout

Inconsistent coffee yield

Funnels overflow

PROBABLE CAUSE

1. Limit Thermostat

CAUTION - Do not eliminate or bypass limit thermostat. Use only Bunn-O-Matic replacement part #29329.1000

2.Control Thermostat

3.Tank Heater(s)

4.Contactor

1.Circuit Breaker

2.Tank Heater(s)

1.Timer

2.Start Switch

1.Timer

2.Solenoid Valve

3.Lime build-up in swing spout and pump tubing.

1.Filters

2.Hole in bottom of funnel ob- structed.

REMEDY

Refer to Service - Limit Thermo- stat for testing procedures. See page19

Refer to Service - Control Ther- mostat for testing procedures. See page 17

Refer to Service - Tank Heater for testing procedures. See page 30

Refer to Service - Contactor for testing procedures. See page 15

Refer to Service - Circuit Breaker for testing procedures. See page 14

Refer to Service - Tank Heater for testing procedures. See page 30

Refer to Service - Timer for testing procedures. See page 31 or 33

Refer to Service - Start Switch for testing procedures. See page 29

Refer to Service - Timer for testing procedures. See page 31 or 33

Refer to Service - Solenoid Valve for testing procedures. See page 27

Remove swing spout and insert deliming rod down into pump tubing as far as possible.

Use Bunn® filters made for the U3 brewer.

Remove obstruction.

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Bunn U3A service manual TROUBLESHOOTING cont PROBLEM, Probable Cause, Remedy

Contents

BUNN-O-MATIC CORPORATION OPERATING & SERVICE MANUALU3 U3A Page BUNN-O-MATIC COMMERCIAL PRODUCT WARRANTYVery Hot Water Use With Care INTRODUCTIONUSER NOTICES ATTENTION TURN OFF WHEN UNATTENDEDELECTRICAL REQUIREMENTS ELECTRICAL INSTALLATION INSTRUCTIONSPLUMBING REQUIREMENTS INITIAL SETUPCE REQUIREMENTS Volumes INITIAL SETUP contADJUSTING BREW VOLUMES FILTER HOLDER CLEANINGCOFFEE BREWING PROBABLE CAUSE TROUBLESHOOTINGPROBLEM PROBABLE CAUSE TROUBLESHOOTING cont PROBLEMPROBABLE CAUSE REMEDYTROUBLESHOOTING cont PROBLEM REMEDY TROUBLESHOOTING cont PROBLEMRefer to Service - Contactor for testing procedures. See page PROBABLE CAUSEREMEDY TROUBLESHOOTING cont PROBLEMFunnels overflow cont Coffee reservoir overflows PROBABLE CAUSEContents SERVICECOMPONENT ACCESS Wire Models and 440V Four Wire Models SERVICE cont2A. 120/208V, 120/240V, 380V THREE WIRE MODELS CONTACTORSERVICE cont BLK Thermal Fuse to Right Tank Heater BLK to Terminal Block L1 SERVICE cont CONTACTOR contBLK to Right Tank Tank HeaterFIG. 6 CONTROL THERMOSTAT SERVICE cont CONTROL THERMOSTATDisconnect the wires from the control thermo Install thermostat and mounting bracket on theFIG. 9 FUSE HOLDER TERMINALS SERVICE contFIG.8 FUSE AND FUSE HILDER With an ohmmeter, check for continuity across SERVICE cont LIMIT THERMOSTATDisconnect the brewer from the power source Voltage SERVICE cont LIQUID LEVEL BOARD AND LEVEL PROBELIQUID LEVEL BOARD AND LEVEL PROBE cont SERVICE contFIG. 15 ON/OFF SWITCH TERMINALS SERVICE cont ON/OFF SWITCHRED to Start Switch, Brew Timer & Liquid Level Board SERVICE cont PUMP ASSEMBLY SERVICE cont RELAY BREWERS W/BREW LOCKOUT BLU from SERVICE cont RELAY BREWERS W/BREW LOCKOUTSERVICE cont SELECTOR SWITCH HALF BATCH OPTION 2. A For 120/208 volt and 120/240 volt three wire, single phase models, 380 volt three wire, three phase models and 380 volt, 440 volt four wire, three phase models, disconnect the black wire from the liquid level board #2 and the white wire on the solenoid. With a voltmeter, check the voltage across the black and the white wire. Connect the brewer to the power source. The indication must be SOLENOIDSERVICE cont SERVICE cont SOLENOID FIG. 24 START SWITCH BREW SERVICE cont START SWITCH BREWFIG. 27 TANK HEATER TERMINALS SERVICE cont TANK HEATERSLEFT FIG. 28 THERMAL FUSES SERVICE cont THERMAL FUSES 230V-CE MODELS ONLYTIMER Early Models To Three Pin Female SERVICE cont TIMER Early ModelscontSERVICE cont DIGITAL TIMER Late Models FIG. 33 DIGITAL TIMER TERMINALS SERVICE cont DIGITAL TIMER Late ModelsNOTE All volume settings must be done with the sprayhead installed NOTE Half-Batch and full batch settings must each be set separatelyFIG. 35 TRANSFORMER TERMINALS SERVICE contTRANSFORMER 380V THREE WIRE MODELS ONLY FIG. 36 MASTER ON/OFF SWITCH LOC SERVICE cont MASTER ON/OFF SWITCH Late Models10060 120/208 VOLTS AC 120/240 VOLTS AC 3 WIRE + GND SINGLE PHASEMAIN ON/OFF SWITCH Late Models only Page080900 Page10060 080900 SCHEMATIC WIRING DIAGRAM U3A & U38A BREWERS PRIOR TO U300004095Page 10060080900 SCHEMATIC WIRING DIAGRAM U3A - CE BREWERS S/N U300004095 - UPPage 10060080900 SCHEMATIC WIRING DIAGRAM U3833Page 10060080900 SCHEMATIC WIRING DIGRAM U3833Page 10060