Vollrath STOELTING U421-I2A User manual

Model U421-I2A & U431-I2A
SERVICE MANUAL
Manual No. 513721 Rev.0

This manual provides basic information about the machine. Instructions and suggestions are
given covering its operation and care.
The illustrations and specifications are not binding in detail. We reserve the right to make
changes to the machine without notice, and without incurring any obligation to modify or pro-
vide new parts for machines built prior to date of change.
DO NOT ATTEMPT to operate the machine until instructions and safety precautions in this
manual are read completely and are thoroughly understood. If problems develop or questions
arise in connection with installation, operation, or servicing of the machine, contact Stoelting.
stoeltingfoodservice.com
Stoelting Foodservice Equipment
502 Highway 67
Kiel, WI 53042-1600
U.S.A.
White Glove Service Network
Phone: [phone]
© 2018 Stoelting

Safety Alert Symbol:
This symbol Indicates danger, warning or caution.
Attention is required in order to avoid serious per-
sonal injury. The message that follows the symbol
contains important information about safety.
Signal Word:
Signal words are distinctive words used throughout
this manual that alert the reader to the existence and
relative degree of a hazard.
CAUTION
The signal word “CAUTION” indicates a potentially
hazardous situation, which, if not avoided, may result
in minor or moderate injury and equipment/property
damage.
A Few Words About Safety
Safety Information
Read and understand the entire manual before
operating or maintaining Stoelting equipment.
This manual provides the operator with information
for the safe operation and maintenance of Stoelting
equipment. As with any machine, there are hazards
associated with their operation. For this reason safety
is emphasized throughout the manual. To highlight
specific safety information, the following safety defini-
tions are provided to assist the reader.
The purpose of safety symbols is to attract your at-
tention to possible dangers. The safety symbols, and
their explanations, deserve your careful attention
and understanding. The safety warnings do not by
themselves eliminate any danger. The instructions
or warnings they give are not substitutes for proper
accident prevention measures.
If you need to replace a part, use genuine Stoelting
parts with the correct part number or an equivalent
part. We strongly recommend that you do not use
replacement parts of inferior quality.
WARNING
The signal word “WARNING” indicates a potentially
hazardous situation, which, if not avoided, may result
in death or serious injury and equipment/property
damage.
CAUTION
The signal word “CAUTION” not preceded by the
safety alert symbol indicates a potentially hazardous
situation, which, if not avoided, may result in equip-
ment/property damage.
NOTE (or NOTICE)
The signal word “NOTICE” indicates information or
procedures that relate directly or indirectly to the
safety of personnel or equipment/property.

TABLE OF
CONTENTS
Section Description Page
1 Introduction
1.1 Description.................................................................................................. 1
1.2 Specifications ............................................................................................. 2
1.3 Component Settings ................................................................................... 4
2 Refrigeration System
2.1 Refrigeration System .................................................................................. 5
2.2 Refrigerant Recovery and Evacuation........................................................ 6
2.3 Refrigerant Charging .................................................................................. 6
2.4 Compressor ................................................................................................ 6
2.5 Condenser .................................................................................................. 8
2.6 Valves ......................................................................................................... 8
A. Thermostatic Expansion Valve (TXV) ..................................................................8
B. Check Valve .........................................................................................................9
C. High Pressure Cutout...........................................................................................9
D. Evaporator Pressure Regulator (EPR).................................................................10
E. Water Valve (Water Cooled Models Only)............................................................ 10
2.7 Solenoid (Air Cooled Remote Only) ........................................................... 11
2.8 Filter Drier................................................................................................... 12
3 Electrical and Mechanical Control Systems
3.1 IntelliTec2 Control ....................................................................................... 13
3.2 Contactors .................................................................................................. 13
3.3 Drive Motor ................................................................................................. 13
3.4 Capacitors .................................................................................................. 14
3.5 Gearbox...................................................................................................... 15
3.6 Condenser Fan Motor (Air-Cooled Only).................................................... 15
3.7 Cab Condenser Fan Motor ......................................................................... 16
3.8 Switches ..................................................................................................... 16
A. Spigot Switch .......................................................................................................16
B. Pump Pressure Switch.........................................................................................17
3.9 Temperature Control Sensor ...................................................................... 18
4 Troubleshooting
4.1 Error Codes ................................................................................................ 19
4.2 Troubleshooting .......................................................................................... 19
4.3 Troubleshooting - Machine ......................................................................... 22

Section Description Page
5 Replacement Parts
5.1 Brushes, Decals, and Lubrication............................................................... 23
5.2 Auger Shaft and Door Parts ....................................................................... 24
5.3 Cab Tubing ................................................................................................. 25
5.4 Trays........................................................................................................... 26
5.5 Panels & Screws ........................................................................................ 26
5.6 Cabinet ....................................................................................................... 27
5.7 Cabinet Evaporator..................................................................................... 28
5.8 Pump Parts................................................................................................. 29
5.9 Spigots........................................................................................................ 31
5.10 Electrical ..................................................................................................... 32
5.11 Motor .......................................................................................................... 33
5.12 Cabinet Condensing Unit............................................................................ 34
5.13 Side View.................................................................................................... 35
5.14 Air-Cooled Remote Condensers................................................................. 36
5.15 Kits and Miscellaneous............................................................................... 37
6 Refrigeration Diagram and Wiring Diagrams
6.1 Refrigeration Diagrams............................................................................... 39
6.2 Wiring Diagrams ......................................................................................... 40
A. U421-48I2A..........................................................................................................40
B. U421-409I2A........................................................................................................41
C. U421-109I2A........................................................................................................42
E. U431-48I2A..........................................................................................................43
F. U431-38I2A..........................................................................................................44
G. U431-18I2A..........................................................................................................45
H. U431-409I2A........................................................................................................46
I. U431-309I2A........................................................................................................47
J. U431-109I2A........................................................................................................48

Service Manual #513721 1 U421-I2A & U431-I2A Model Machines
SECTION 1
DESCRIPTION AND SPECIFICATIONS
1.1 DESCRIPTION
The Stoelting U421-I2A and U431-I2A floor model ma-
chines are pressure fed. They are equipped with fully
automatic controls to provide a uniform product.
This manual is designed to assist qualified service per-
sonnel with troubleshooting and repairing the U421-I2A
and the U431-I2A.
NOTE
Thesemachinesare offeredwithtwotypesof spigot
handles,swing gateand pull-down. Theswing gate
styleis opened bymoving the handle to theleft and
must be closed when finished dispensing. The
pull-down style is opened by pulling downwards
and are self-closing.
Figure 1-1 Model U431-I2A
Figure 1-1 Model U421-I2A

Service Manual #513721 2 U421-I2A & U431-I2A Model Machines
1.2 SPECIFICATIONS
Air Cooled
U421-I2A & U431-I2A Air Cooled Remote U421-I2A & U431-I2A Water Cooled U421-I2A & U431-I2A
Dimensions Machine with crate Machine with crate Machine with crate
width 26-3/4’’
(67,9 cm)
34’’
(86,4 cm)
26-3/4’’
(67,9 cm)
34’’
(86,4 cm)
26-3/4’’
(67,9 cm)
34’’
(86,4 cm)
height 68-3/4’’
(174,6 cm)
78’’
(198,1 cm)
67-3/4’’
(172,1 cm)
78’’
(198,1 cm)
67-1/2’’
(171,5 cm)
78’’
(198,1 cm)
depth 39-1/2’’
(100,3 cm)
48’’
(121,9 cm)
39-3/4’’
(101,0 cm)
48’’
(121,9 cm)
39-1/2’’
(100,3 cm)
48’’
(121,9 cm)
Weight 785 lbs
(356,0 kg)
935 lbs
(424,1 kg)
760 lbs
(344,7 kg)
908 lbs
(411,8 kg)
760 lbs
(344,7 kg)
908 lbs
(411,8 kg)
Electrical 1 PH 3 PH 1 PH 3 PH 1 PH 3 PH
circuit ampacity
(per barrel) 32A 20A 36A Left /
31A Right 20A 32A 20A
overcurrent protection
device (per barrel) 50A 30A 50A Left /
45A Right 30A 50A 30A
The machine requires one dedicated electrical circuit per barrel.
Compressor Two - 19,000 Btu/hr
Cabinet - 1,300 Btu/hr Compressor (R-134a)
Drive Motor Two - 2 hp
Cooling Air cooled units require 6”
(15,2 cm) air space on all
sides and open at the top.
Remote air cooled
requires two remote
condensers and two
precharged line sets.
Water cooled units require
1/2” N.P.T. water and
drain fittings. Maximum
water pressure of 130
psi. Minimum water flow
rate of 3 GPM per barrel.
Ideal EWT of 50°-70°F.
The machine requires 6”
(15,2 cm) air space on
all sides for the cabinet
refrigeration system.
Mix Storage Up to six 5-gallon bags
Freezing Cylinder
Volume Two - 1.33 gallon (5,03 liters)

Service Manual #513721 3 U421-I2A & U431-I2A Model Machines
Menu Display U421 I2A & U431 I2A
Basic Enable Control Temp/Temp
CutOut Consist Offset 5
CutIn Consist Offset 55
CutIn Temp 40 °F
CutOut Temperature 12 °F
Cycles In Serve Mode 50
Advanced Standby On Time 10 sec
Standby Off Time 360 sec
Standby Time 120 min
Stir On 10 sec
Stir Off 1200 sec
Sleep 2 CutIn 70 °F
Sleep 2 CutOut 54 °F
Default Off Time 900 sec
Storage Storage Refrigeration Active
Storage CutIn 39 °F
Storage CutOut 36 °F
Storage Offset 2 °F
Storage Off Time 4 min
Storage On Time 360 sec
Storage Max On 10 min
Storage Recovery 1 min
Storage Too Warm 50 °F
Storage Too Warm 2 hr
U421-I2A & U431-I2A
Refrigerant R-404A
Charge A/C - 48 oz W/C - 36 oz
Remote - 224 oz
Suction Pressure 19-21 psig
Discharge Pressure
at 80ºF Ambient
A/C - 235-240 psig
W/C - 225-235 psig
Cabinet
Refrigerant R-134A
Charge 8 oz
EPR Valve 32-34 psig

Service Manual #513721 4 U421-I2A & U431-I2A Model Machines
1.3 COMPONENT SETTINGS
Following are the settings for the components in the
U421-I2A and U431-I2A machines.
A. COMPRESSOR WINDINGS
When testing the compressor windings the resistance
through the windings should be as follows:
B. CAPACITORS
Refer to the following table for the capacitance of all the
capacitors in the machine:
C. PUMP PRESSURE SWITCH
The pump pressure switch, located in the cabinet, main-
tains 21-24 psig in the mix line.
°F Resistance °F Resistance
-22 176950 40 26100
-20 165200 42 24725
-18 154300 44 23400
-16 144200 46 22175
-14 134825 48 21000
-12 126125 50 19900
-10 118050 52 18875
-8 110550 54 17900
-6 103550 56 17000
-4 97075 58 16125
-2 91025 60 15325
0 85400 62 14550
2 80150 64 13825
4 75275 66 13150
6 70725 68 12500
8 66475 70 11875
10 62500 72 11300
12 58800 74 10750
14 55325 76 10250
16 52100 78 9750
18 49075 80 9300
20 46250 82 8850
22 43600 84 8450
24 41125 86 8050
26 38800 88 7675
28 36625 90 7325
30 34575 92 7000
32 32675 94 6675
34 30875 96 6375
36 29175 98 6100
38 27600 100 5825
D. TEMPERATURE CONTROL SENSOR
The following table shows the relationship between the
thermistor resistance and the suction line temperature.
Compressor Electrical S to C R to C
282106 1 PH 60Hz 1.340.94
282107 3 PH 60Hz 1.531.21
282108 3 PH 50Hz 3.811.33
Rating
Capacitor Part MFD VAC
Cab Compressor 230667 80 MFD 220 VAC
Compressor - Run 231047 45 MFD 370 VAC
Compressor - Start 230638 88-106 MFD 330 VAC
Drive Motor - Run 231075 30 MFD 370 VAC
Drive Motor - Start 230622 200 MFD 250 VAC
Fan Motor 230654 5 MFD 400 VAC
Pump Motor 1171960 15 MFD 370 VAC