Bunn Nitron Cold Draft Service & Repair Manual
SERVICE & REPAIR MANUAL
BUNN-O-MATIC CORPORATION
PHONE: (217) 529-6601 FAX: (217) 529-6644
To ensure you have the latest revision of the Operating Manual, or to view the Illustrated Parts Catalog, Programming
Manual, or Service Manual, please visit the Bunn-O-Matic website, at www.bunn.com. This is absolutely FREE, and the
quickest way to obtain the latest catalog and manual updates. For Technical Service, contact Bunn-O-Matic Corporation
at 1-800-286-6070.
55124.0000A 02/18 ©2018 Bunn-O-Matic Corporation
POST OFFICE BOX 3227
SPRINGFIELD, ILLINOIS 62708-3227
www.bunn.com
BUNN-O-MATIC COMMERCIAL PRODUCT WARRANTY
Bunn-O-Matic Corp. (“BUNN”) warrants equipment manufactured by it as follows:
1) Airpots, thermal carafes, decanters, GPR servers, iced tea/coffee dispensers, MCR/MCP/MCA single cup brewers, thermal servers and ThermoFresh® servers (mechanical and digital) 1 year parts and 1 year labor.
2) All other equipment - 2 years parts and 1 year labor plus added warranties as specified below:
a) Electronic circuit and/or control boards - parts and labor for 3 years.
b) Compressors on refrigeration equipment - 5 years parts and 1 year labor.
c) Grinding burrs on coffee grinding equipment to grind coffee to meet original factory screen sieve analysis - parts and
labor for 4 years or 40,000 pounds of coffee, whichever comes first.
These warranty periods run from the date of installation BUNN warrants that the equipment manufactured by it will be
commercially free of defects in material and workmanship existing at the time of manufacture and appearing within the
applicable warranty period. This warranty does not apply to any equipment, component or part that was not manufactured
by BUNN or that, in BUNN’s judgment, has been affected by misuse, neglect, alteration, improper installation or operation,
improper maintenance or repair, non periodic cleaning and descaling, equipment failures related to poor water quality,
damage or casualty. In addition, the warranty does not apply to replacement of items subject to normal use including but
not limited to user replaceable parts such as seals and gaskets. This warranty is conditioned on the Buyer 1) giving BUNN
prompt notice of any claim to be made under this warranty by telephone at (217) 529-6601 or by writing to Post Office Box
3227, Springfield, Illinois 62708-3227; 2) if requested by BUNN, shipping the defective equipment prepaid to an authorized
BUNN service location; and 3) receiving prior authorization from BUNN that the defective equipment is under warranty.
THE FOREGOING WARRANTY IS EXCLUSIVE AND IS IN LIEU OF ANY OTHER WARRANTY, WRITTEN OR ORAL, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF EITHER MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE. The agents, dealers or employees of BUNN are not authorized to make
modifications to this warranty or to make additional warranties that are binding on BUNN. Accordingly, statements by such
individuals, whether oral or written, do not constitute warranties and should not be relied upon.
If BUNN determines in its sole discretion that the equipment does not conform to the warranty, BUNN, at its exclusive option while the equipment is under warranty, shall either 1) provide at no charge replacement parts and/or labor (during the
applicable parts and labor warranty periods specified above) to repair the defective components, provided that this repair
is done by a BUNN Authorized Service Representative; or 2) shall replace the equipment or refund the purchase price for
the equipment.
THE BUYER’S REMEDY AGAINST BUNN FOR THE BREACH OF ANY OBLIGATION ARISING OUT OF THE SALE OF THIS
EQUIPMENT, WHETHER DERIVED FROM WARRANTY OR OTHERWISE, SHALL BE LIMITED, AT BUNN’S SOLE OPTION
AS SPECIFIED HEREIN, TO REPAIR, REPLACEMENT OR REFUND.
In no event shall BUNN be liable for any other damage or loss, including, but not limited to, lost profits, lost sales, loss of
use of equipment, claims of Buyer’s customers, cost of capital, cost of down time, cost of substitute equipment, facilities
or services, or any other special, incidental or consequential damages.
392, A Partner You Can Count On, Air Infusion, AutoPOD, AXIOM, BrewLOGIC, BrewMETER, Brew Better Not Bitter, BrewWISE, BrewWIZARD, BUNN Espress, BUNN Family Gourmet, BUNN Gourmet, BUNN Pour-O-Matic, BUNN, BUNN with
the stylized red line, BUNNlink, Bunn-OMatic, Bunn-O-Matic, BUNNserve, BUNNSERVE with the stylized wrench design,
Cool Froth, DBC, Dr. Brew stylized Dr. design, Dual, Easy Pour, EasyClear, EasyGard, FlavorGard, Gourmet Ice, Gourmet
Juice, High Intensity, iMIX, Infusion Series, Intellisteam, My Café, Phase Brew, PowerLogic, Quality Beverage Equipment
Worldwide, Respect Earth, Respect Earth with the stylized leaf and coffee cherry design, Safety-Fresh, savemycoffee.com,
Scale-Pro, Silver Series, Single, Smart Funnel, Smart Hopper, SmartWAVE, Soft Heat, SplashGard, The Mark of Quality in
Beverage Equipment Worldwide, ThermoFresh, Titan, trifecta, TRIFECTA (sylized logo), Velocity Brew, Air Brew, Beverage
Bar Creator, Beverage Profit Calculator, Brew better, not bitter., Build-A-Drink, BUNNSource, Coffee At Its Best, Cyclonic
Heating System, Daypart, Digital Brewer Control, Element, Milk Texturing Fusion, Nothing Brews Like a BUNN, Picture
Prompted Cleaning, Pouring Profits, Signature Series, Sure Tamp, Tea At Its Best, The Horizontal Red Line, Ultra are either
trademarks or registered trademarks of Bunn-O-Matic Corporation. The commercial trifecta® brewer housing configuration is a trademark of Bunn-O-Matic Corporation.
2
55124 031314
INTRODUCTION
Safety first!
To avoid electrical shock, unplug dispenser from power source before servicing inside.
Basic Maintenance
In order to maintain proper machine operation, a Preventative Maintenance schedule must be performed on a
regular basis.
The following procedures pretain to all versions in the Nitron family of machines unless otherwise noted.
CONTENTS
Warranty ...................................................................................................................................2
User Notices .............................................................................................................................3
Site Preparation .......................................................................................................................3
Preventive Maintenance
Recommended Daily Cleaning ...........................................................................................4
Preventive Maintenance Schedule ....................................................................................... 5
Troubleshooting ........................................................................................................................ 6
Service .................................................................................................................................... 17
Electrical Schematics ..............................................................................................................51
USER NOTICES
All notices on this equipment are written for your protection. All notices are to be kept in good condition.
Replace any unreadable or damaged labels.
SITE PREPARATION
A minimal clearance is required between the dispenser sides and the wall or another appliances.For optimum
performance, do not allow warm air from surrounding machines blow on the JDF dispenser. Leave some space
so the dispenser can be moved for cleaning.
3
55124 021418
Recommended Daily Cleaning Instructions
The use of a damp cloth rinsed in any mild, non-abrasive, liquid detergent is recommended for cleaning all surfaces on Bunn-O-Matic equipment. Do NOT clean this equipment with a water jet device.
1. Open dispenser door.
Lift up on product containers to disconnect
them from the machine
inlet.
5. Remove dispenser
nozzles and drip tray.
Wash all parts in warm
soapy water.
2. Close door, place an
empty container under
the dispense nozzles.
Brush Storage
Lubricant Shelf
2. Dispense from each
station until clear water
flows from the dispense nozzle.
6. Use brush to clean
through dispense nozzles.
4. Open dispenser door
and reconnect all product containers.
7. Use brush to clean nitro
insert.
8. Use brush to clean nozzle connection ports on
machine. BUNN Part
No. 49827.0000.
9. Apply small amount
of food grade lubricant to o-ring on nozzles. BUNN Part No.
M2550.0001.
12. Dispense from each
station until finished
product flows from the
dispense nozzles.
10. With a warm soapy
cloth, wipe down interior of cabinet and
splash panel area behind dispensing nozzles.
Recommended Weekly Cleaning
REAR OF
DISPENSER
13. Remove Air Filter from
outside rear panel of
dispenser.
4
11. Replace drip tray and
dispense nozzles. Be
sure to install nitro
nozzle in left dispense
station.
DIRTY
CLEAN
14. Wash Filter using warm soapy water,
rinse using water flow from faucet.
Shake out excess water then re-install
on rear panel of dispenser.
55124 021418
REQUIRED REGULAR MAINTENANCE:
When performing Daily-Weekly Cleaning procedures, inspect o-rings, seals, and bushings for signs of wear or
damage and replace immediately.
Check and/or replace every 6 months or as required:
39690.0000 Pump Tube Replacement Kit (Includes items indented below)
28755.1011 Tube, Norprene .25" ID x 17.0" lg
32732.0000 Clamp .39"/.48"
32656.0000 Fitting, Elbow .25" Barb x .38" Barb
21275.0003 Clamp .57"/.70"
34325.0032 Hose, Flex .38" ID x 5.25" lg
5
55124 021418
TROUBLESHOOTING
A troubleshooting guide is provided to suggest probable causes and remedies for the most likely problems encountered.
If the problem remains after exhausting the troubleshooting steps, contact the Bunn-O-Matic Technical Service Department.
• Inspection, testing, and repair of electrical equipment should be performed only by qualified service personnel.
• All electronic components have 120-240 volt ac and low voltage dc potential on their terminals. Shorting of terminals
or the application of external voltages may result in board failure.
• Intermittent operation of electronic circuit boards is unlikely. Board failure will normally be permanent. If an intermittent
condition is encountered, the cause will likely be a switch contact or a loose connection at a terminal or crimp.
• Solenoid removal requires interrupting the water supply to the valve. Damage may result if solenoids are energized for
more than ten minutes without a supply of water.
• The use of two wrenches is recommended whenever plumbing fittings are tightened or loosened. This will help to avoid
twists and kinks in the tubing.
• Make certain that all plumbing connections are sealed and electrical connections tight and isolated.
WARNING – • Exercise extreme caution when servicing electrical equipment.
• Unplug the dispenser when servicing, except when electrical tests are specified.
• Follow recommended service procedures.
• Replace all protective shields or safety notices.
PROBLEM
Cold Water Circulation
Dispense stations not working.
Note: Cooling failure or excessive
cabinet temperatures for more
than 4 hours will result in dispense
lockout or no dispense.
Note: Reset fault/timer by unplugging unit.
Dispense nozzle dripping/won't stop
dispensing.
PROBABLE CAUSE
1. Cabinet cooling fan.
2. Bath recirculation pump.
3. Restricted water flow to cabinet
water coil and bath.
1. Juice residue causing oring on
dispense nozzle to lose vacuum.
REMEDY
Replace fan (24vdc).
Note: Fan receives power when the
dispenser is powered.
A) If not running, check refrigeration switch and wiring for proper
continuity.
B) Check for 120V or 230V AC at
pump. Replace pump.
Check for kinked hose.
A) Remove dispense nozzles and
stout insert. Clean nozzles and oring
in mild detergent solution.
B) Use soft bristle brush and mild
detergent solution to clean dispense
valve area that dispense nozzles are
seated.
6
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Refrigeration
Dispense stations not working.
Note: Cooling failure or excessive
bath and cabinet temperatures for
more than 4 hours will result in
dispense lockout or no dispense.
PROBABLE CAUSE
1. Compressor ON/OFF switch.
2. Dirty condenser filter or fins.
3. Condenser fan not running.
4. Compressor relay not activating.
REMEDY
Check for "ON" position or no continuity - replace switch.
Clean filter and fins or replace condenser filter. (Filter not supplied on
some machines).
A) Check for 120V or 230V AC. Replace fan motor or check fan blades
for obstructions.
B) Check compressor LED on circuit
board. If ON, relay coil should have
power (120 or 230 VAC).
Check compressor relay coil for 120
or 230vac.
NOTE: Always check power with
coil attached. If compressor LED is
ON and no 120 or 230vac - replace
board. If yes, 120 or 230vac - replace relay.
Note: Relay contacts are normally
open.
5. Compressor not running.
6. Compressor running and not
cooling.
7. Low water bath or bath fill valve
failed.
Check compressor thermal overload
(N/C). If open check for dirty condenser filter or adequate ventilation
and space around machine.
Check refrigeration system for leaks
and proper charge.
Check Dispense switch is set to ON
and sight gauge shows full water
bath. If sight gauge is low, press
Dispense switch to OFF. Wait a few
seconds. Press Dispense switch
to ON. Bath will automatically start
filling water bath after 30 seconds.
7
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Dispenser Locked Out
Dispense stations not working.
Cooling system failure.
Dispense station not working
All stations dispense concentrate
only
PROBABLE CAUSE
1. Check Dispense Lockout switch.
1. Refrigeration or cold water recirculation system.
1. Dispense Lockout switch set to
OFF position.
2. Dispense switch failed
Main water supply
REMEDY
(A) Set switch to ON position.
(B) Check switch and harness for
proper continuity.
Check all previous items that pretain to refrigeration or cold water
recirculation
Place switch in ON position.
Check switch and harness for proper
continuity.
Check for ON position.
Frozen bath
Inlet water valve failed
A) Compressor relay/contacts
shorted - replace relay.
B) Recirculating pump - replace or
check for kinked flex line.
A) Check for 120V or 230V power
when dispensing. If yes, replace
valve. If no, check harness for
proper continuity. Then replace
circuit board if needed.
8
55124 021418
TROUBLESHOOTING (Continued)
PROBLEM
Dispense station
concentrate only
Dispense station
water only
PROBABLE CAUSE REMEDY
Water solenoid
Replace solenoid (24vdc) or check
wire connection between water valve
and main control board.
Concentrate out
Replace refill concentrate container
or BIB
Product pump not pumping
Check for proper counterclockwise
rotation of pump rollers. If counterclockwise, replace pump tubing.
If clockwise, wire connection to
pump is reversed. Switch wires on
terminals.
Pump not turning
A) Check speed setting on circuit
board and increase speed (turn
clockwise)
B) Check for d.c. power to pump
motor. If yes, replace motor assy. If
no, check harness for proper continuity. Then replace circuit board if
needed.
9
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Water leak filling drip tray or around
dispense deck area
Water leaking beneath machine
PROBABLE CAUSE
1. Initial fill/setup
2. Dispense deck
3. Water pressure greater than
100psi
1. Bath tank overflow.
REMEDY
Some expansion normal. May fill
drip tray during initial ice block
formation
Inspect or replace fittings clamps,
o-rings, solenoids and quick disconnect fittings.
NOTE: Dispense deck area slopes to
drain tube that leads to the drip tray.
Install water pressure regulator and
reduce to 50 psi.
A) Check all internal water connections.
B) Check internal plumbing connections.
2. Condensation from cabinet cooling coil.
C) Check bath float switch
Check for routing of condensation
tube to water bath.
10
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Unit is not working
Difficulty brixing and/or weak beverage
PROBABLE CAUSE
1. Step-down transformer.
2. Main control board.
1. Product viscosity or too cold.
2. Low water pressure.
3. High water pressure.
4. Dispense valve adjustment setting.
REMEDY
Check for 120/24 or 230/24 vac. If no
24vac reading, replace step-down
transformer.
If 24 vac present and no LED’s lit,
replace control board.
Thorough thaw of product before
use (35° - 40°)
Maintain 30 psi or higher and a
minimum dynamic flow rate of 4.5
fl oz/sec.
Over 100 psi, install a pressure
regulator and set to 50 psi.
A) Perform 3 second water dispense
test. Factory setting is 133 ml in 3
second dispense.
Difficulty brixing and/or weak beverage
Difficulty brixing bag-in-box
5. Brix ratio.
1. Pump tubing.
2. Use of portable water pump.
Vacuum leak
B) Adjust water to 133 mL/3 sec..
Once water is set, adjust motor
speed to achieve brix degrees.
Check for proper brix ratio per
product using Ratio method and
or refractometer method.
Inspect, clean, or replace tubing
and pump rotor/rollers for ease of
rotation.
A) Follow plumbing requirements
for pressure and flow rate.
B) Source another portable pump
or water supply that meets requirements.
Inspect all lines and connections
from bag-in-box connector to bottle
adapter assembly.
11
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Only Water Flowing from Faucet
Head on Beverage Thinner than
Desired
PROBABLE CAUSE
1. Bag-in-Box (BIB) or caddy is
empty.
2. BIB or caddy is not engaged in
bottle adapter properly.
1. System is not set to temperature yet (ice bank not fully
formed).
REMEDY
1. Change BIB to full BIB or refill
the caddy with more product.
2. Lift BIB or caddy out of adapter and seat it back down properly. Follow step-by-step instructions on priming product
through the system.
1. Wait until system is fully cooled
and ice bank fully formed
before setting preferred N2
pressure. Check Compressor
switch is set to ON and sight
gauge shows full water bath. If
water bath sight gauge is low,
press Dispense switch to OFF.
Wait a few seconds. Press Dispense switch to ON. Bath will
automatically start filling water
bath after 30 seconds.
2. a) Tank regulator is below 125
psi (red LED Nitrogen “Out”
light is flashing on dispenser
door).
b) Gas leak on tank regulator.
2. a) Adjust tank regulator by
turning the T-handle clockwise
until needle reaches 125 psi.
Dispense a drink to make sure
needle stays set at 125 psi.
b) If gas is leaking from tank
regulator, replace tank regulator by contacting manufacturer or supplier.
12
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Coffee is Weaker than Desired
Coffee is Stronger than Desired
PROBABLE CAUSE
1. BIB or caddy is empty.
2. Product pump tubing is worn.
3. Build-up is occurring in nozzle
and system needs cleaning.
4. Brix is off target and needs adjustment.
1. Water supply is turned off or
too low water pressure from
source/inlet.
REMEDY
1. Change to full BIB or replenish
caddy with more product.
2. Contact authorized service
agent or perform product tubing replacement if authorized
to do so.
3. Remove nozzles and clean
with sanitizing solution to remove build-up. Follow Care
and Cleaning instructions and
run sanitizing solution through
system.
4. Follow set-up instructions to
adjust Brix.
1. Assure required water connection was made properly and if
there’s a shut-off valve, make
sure shut-off valve is open.
Check that water inlet pressure has dynamic operating
pressure between 30 to 90 psi.
If below 30 psi, install water
booster pump for adequate
water pressure to supply line
of dispenser.
2. Brix is off target and needs adjustment.
13
2. Follow set-up instructions to
adjust Brix
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Nothing Flowing from Nozzles
Product Pouring Too Warm and/or
Inside Cabinet Too Warm
PROBABLE CAUSE
1. Dispense switch is OFF.
2. Gas, coffee, and water not
connected.
1. System has not reached temperature (ice bank not fully
formed).
REMEDY
1. Turn Dispense switch ON.
2. Assure all required connections are made according to
set-up instructions before operating the system.
1. Wait until system is fully
cooled and ice bank fully
formed. Check Compressor
switch is set to ON and sight
gauge shows full water bath. If
water bath sight gauge is low,
press Dispense switch to OFF.
Wait a few seconds. Press Dispense switch to ON. Bath will
automatically start filling water
bath after 30 seconds.
2. BIB or caddy is ambient temp
and needs to cool down.
3. Water bath pump not running.
2. Best practice is to use a chilled
BIB or caddy for proper nitrogenation. If using ambient
concentrates, chill BIB or caddy first prior to using.
3. Confirm the compressor/water
bath pump switched is turned
ON. Confirm the water bath
pump and compressor are
running.
14
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Irregular Flow from Nozzle
1. Flow is pulsating/ hammering
2. Flow coming out at an angle
3. Flow rate is slow
PROBABLE CAUSE
1. The product pump speed is set
too high (at max) to dispense
a lower ratio product (below
4:1).
2. The nozzle has accumulated
build-up or debris.
3. a) The nozzle has accumulated
build-up or debris
b) The water needle valve on
right-side of deck may be set
too low (only affects Still Dispense station)
c) The system needs cleaning
REMEDY
1. Use a more appropriate concentrate (between 4:1 to 11:1)
and adjust the product dial to
the proper Brix setting.
2. Remove nozzles and clean
with sanitizing solution to remove build-up. Follow Care
and Cleaning instructions and
run sanitizing solution through
system.
3. a) Remove nozzles and clean
with sanitizing solution to remove build-up. Follow Care
and Cleaning instructions and
run sanitizing solution through
system.
b) Water flow rate should be
factory pre-set to 133 ml (4.5
oz) per 3 second dispense.
To verify, switch to Program
mode. Place a graduated measuring cylinder under the dispense nozzle, pull and release
the tapper handle 3 times. The
dispenser will then dispense
an amount of water for 3 seconds. If water flow rate is set
too low, adjust the water needle valve using a small flathead
screwdriver and turning the
needle counter-clockwise.
15
c) Clean the system by follow-
ing the Care and Cleaning instructions.
55124 021418
TROUBLESHOOTING (cont.)
PROBLEM
Unit Performing Inconsistently
(Brix/Nitro fluctuating wildly or
outside normal range)
PROBABLE CAUSE
1. System was installed/set-up
incorrectly or has been placed
in an environment with unacceptable conditions:
a. Incorrect water line size
b. Incorrect gas line size
c. Fluctuations in water or
gas supply pressures
d. Ambient temperature too
high or low
2. System has internal malfunction and needs service by a
technician
REMEDY
1. a) Install a water line that is
in accordance with machine
specifications.
b) Install a gas line that is in
accordance with machine
specifications.
c) Assure the unit is being fed
consistent and constant gas
and water pressure.
d) Place the unit in a location
in accordance with machine
specifications.
2. Call Customer Support for assistance.
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55124 021418
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