NuAire NU-99338JE User manual

NuAire Ultra Low Temperature Freezer Service Manual OM0290
OM0290 Revision 2
May/2020 Page 1 of 60 Release Date:5/20/2020
NuAire Ultra Low Temperature Freezer
Service Manual
Model Picture
NU-99338JE/338JG/338JGA
NU-99486JE
NU-99578JE/578JGA/578JGA
NU-99728JE/728JGA/728JGA
NU-99828JE/828JG
NU-99420JE
NU-99420JG

NuAire Ultra Low Temperature Freezer Service Manual OM0290
OM0290 Revision 2
May/2020 Page 2 of 60 Release Date:5/20/2020
1 Contents
1. Contents..................................................................................................................... 2
2. Product Characteristics and Model Meaning ............................................................ 3
3. Product Promotionial Points...................................................................................... 4
4. Product Appearance Structure & Internal Structure Diagram .................................. 5
5.Product Component Structure & Names.................................................................... 6
6. Product Use Introduction & Product Improvement Introduction ........................... 14
7. Main Technical Parameters of the Product ............................................................. 18
8. Case Prevention Measures, Product Use and Daily Maintenance Knowledge....... 21
9. Schematic Diagram and Wiring Diagram of the System ........................................ 26
10. Specific Control, Work Principle and Parameters................................................. 28
11. Refrigeration Cycle Prospective and Plan............................................................. 32
12. Installation & Disassembly Process ...................................................................... 33
13.Typical Troubles & Solutions and Common Q&A................................................ 35
14.Post-maintenancenormal cooling curve data of refrigeration system....................52

NuAire Ultra Low Temperature Freezer Service Manual OM0290
OM0290 Revision 2
May/2020 Page 3 of 60 Release Date:5/20/2020
2 Product Characteristics and Model Meaning
2.1. Main Functions and Characteristics of the Product
2.1.1. The applicable temperature scope in the ultra-low temperature freezer is -40~-86℃;
2.1.2. The freezer has the balanced internal and external pressure design and its doors can be opened
and closed easily;
2.1.3. The display panel is divided into the working area and alarm area to display the machine startup
condition, network connection condition, the voltage increase or decrease and locking condition.
Meanwhile, the high/low temperature alarm and the temperature in the freezer can be set;
2.1.4. The digital display can display the temperature in the freezer, the ambient temperature and the
input voltage, etc. at the same time;
2.1.5. Multiple failure alarms (high/low temperature alarm, sensor alarm, high/low voltage alarm, hot
condenser alarm, improper ambient temperature alarm, door opening alarm, low battery capacity alarm
and power failure alarm);
2.1.6. Two kinds of alarm methods (acoustic silence alarm and light flicker alarm) and multiple protection
functions (start delay protection, low voltage compensation protection and HV compensation protection);
2.1.7. This product has the network function with RS-232 and RD-485 data interface and can be
connected with the computer. The temperature in the freezer is displayed, the alarm information is
displayed via the computer and it is also possible to control the temperature and monitor if the
equipment works properly via the computer;
2.1.8. It has the remote-control alarm function and can connect the alarm device to other rooms to
realize the alarm function;
2.1.9. HV/LV automatic compensation function;
2.1.10. The freezer is equipped with trundles for moving, locking and supporting flexibly and realizes the
micro-adjustment according to the requirement;
2.1.11. The recorder, network monitoring system, message service and stainless-steel rack are
configurable
2.2 Model Meanings
NU 99 578 JE
Energy Savings Model
Effective volume of product
Ultra-low Freezer Designation (ULT)
Nuaire Product designation
Voltage characteristics

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3. Product Promotional Points
3.1 Temperature Control:
The temperature is controlled by computer and displayed digitally, its adjustment unit is 1℃and the
adaptable temperature scope is -40~-86℃;
3.2 Safety Control:
3.2.1 Multiple failure alarm (high/low temperature alarm, sensor alarm, door opening alarm, hot
condenser alarm, improper ambient temperature alarm, improper voltage alarm, low battery capacity
alarm and power failure alarm);
3.2.2 Two alarm modes (acoustic silence alarm and light flicker alarm) and multiple protection functions
(start delay protection);
3.2.3 All independent components are connected to the ground safely;
3.3 Refrigerating system:
3.3.1 Optimal cascade refrigerating technology, imported compressor and strong refrigerating capacity;
3.3.2 High-density thermal insulation layer, good insulation effect;
3.3.3 Independent multi-layer sealing structure and heat insulation technology, can avoid frosts
effectively;
3.3.4 Special design of low temperature computer control, avoid that the cascade system controls the
low temperature compressor incorrectly;
3.4 Individualized Design:
3.4.1 The LED display panel can display the temperature in the freezer, set temperature, ambient
temperature, input voltage, can set the high /low temperature alarm and the temperature in the freezer
and also has the failure alarm function;
3.4.2 Adjustable rack design for storing and fetching goods easily;
3.4.3 Safety door lock, please avoid opening door casually;
3.4.4 Integrated handle innovation design and compact trundle design, flexible and inconvenient;
3.4.5 Have network function and remote alarm function.;
3.5 VIP
It is made of PU foaming layer + 25mm VIP vacuum insulation material and can reduce the equipment
coverage to the maximum extent;
3.6 Noise
Lower noise, leading in the world comfortable working environment and barely audible for the user.

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OM0290 Revision 2
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4. Product Appearance Structure & Internal Structure Diagram
4.1 Energy saving series:NU-99486JE NU-99578JE/578JGA/578JGA
NU-99728JE/728JGA/728JGA NU-99828JE/828JG
4.2 Slim line series：NU-99338JE/338JG/338JGA
4.3 Chest series
：
NU-99420JE NU-99420JG
Front View
Internal Structural View
Rear View
Front View
Internal Structural View
Rear View
Front View
Open door View

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5. Product Component Structure & Names
5.1 Display:NU-99486JE NU-99578JE/578JGA/578JGA NU-99420JE NU-99420JG
NU-99728JE/728JGA/728JGA NU-99828JE/828JG NU-99338JE/338JG/338JGA
NU-99420JE NU-99420JG
Locked
Network
Run
Regulator
Backup
High temp. alarm
Low temp.
alarm
Door open
Power failure
Probe
failure
Low
battery
Hot
condenser
High
ambient
temp.
Function
Silence alarm

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5.2.1 Cabinet Structure
Right refrigeration
panel
Left refrigeration
panel
Power switch cover
Inner door
：
PU foamed
Inner door seals can be
replaced.
External door
：
PU foam with
VIP
External door seals can be
replaced.
Recorder mounting
panel
Air intake grill
Inner door latch
：
remove the
side screws when replaced
One piece
cabinet frame
Main cabinet
sensor shield
Removable
stainless steel
pilaster
Horizontal bar
Zinc coated steel
Process
porthole
Test
porthole 2
Test
porthole 1
5V Power
outlet

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Internal door handle
Threading hole at the back of the
freezer, four-channel structure
External door
handle
Foam internal door
Internal door
sealing strip
External door
sealing strip
Balance
hole
Magnetic control switch box for
door opening alarm

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5.3.1 Electric cabinet：NU-99486JE NU-99578JE/578JGA/578JGA
NU-99728JE/728JGA/728JGA NU-99828JE/828JG NU-99338JE/338JG/338JGA
Condenser
fan
RS-232/485Port
Location
(Not Shown)
Control
board
High temp stage
Relay
Terminal
strip
Battery charge
switch
Remote alarm
terminal
Power switch
Battery
Low temp stage
Relay
Filter
Condenser fan

NuAire Ultra Low Temperature Freezer Service Manual OM0290
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Hi Temp Stage
Compressor
Low temp
compressor
Condenser
fan motor
Fan motor
Boost
Buck
Cap
tube
heater
Main sensor
connector
Heat
exchanger
connector
Condenser
sensor
connector
Board check button: press this button to
observe if all relay lights will take turn to
light up.
Remote
alarm
connector
Voltage calibration
screw
Connector
for display
board
Pressure balance
port heater
connector (yellow)
Battery charge
connector
(white)
5V power
connector
Door alarm
connector
USB signal
connector
Temperature
adjustment
screw
Display board
connector
Ambient sensor
connector
RS232/485
connector
Voltage switch
(115V or 230V)

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5.3.2 Junction box:NU-99420JE NU-99420JG
Battery
Control board
Compressor relay
Terminal strip
USB power board
Filter
Power switch
Battery switch
Remote alarm
contacts
RS-232/485Port
Location
(Not Shown)

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5.4 Refrigeration
5.4.1 Refrigeration System :NU-99486JE NU-99578JE/578JGA/578JGA
NU-99728JE/728JGA/728JGA NU-99828JE/828JG NU-99338JE/338JG/338JGA
High stage
liquid
accumulator
High
temperature
filter dryer
Low
temperature
filter dryer
Perimeter halo
tube
High Temp
stage condenser
Low temp stage
oil separator
Low
temperature
stage pressure
control
High stage
compressor
Low
temperature
compressor
Filter

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5.4 .2 Refrigeration system: NU-99420JE NU-99420JG
High
temperature
compressor
High stage filter
dryer
Condenser
Low temperature
stage filter dryer
Condenser
Oil
separator
High stage liquid
accumulator
Low
temperature
compressor

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6. Product Use Introduction & Product Improvement Introduction
6.1 Unlocking:
Press the key “UP” or “DOWN”. When “00” is displayed on the display panel, adjust the key "UP" to “06”
(“06” is the default password) and then press the key “ SET” for 3 seconds. When the lock indicator turns
off, the unit is unlocked.
6.2 Temperature Setting Operation:
Pressing the key “SET” under the unlocking state will cycle through the Inner temp, High Temp alarm,
and low Temp alarm setpoints. After their indicators turn on, press the key “UP” or “DOWN” to regulate
the temperature.
6.3 Notes
6.3.1 After you install or move the equipment for the 1st time, please rotate its horizontal trundles
clockwise to make them stand on the ground and ensure the freezer does not move while using. After
installation and fixation, wait 24 hours to turn unit on.
6.3.2 The ambient temperature shall be kept below 28℃. (If the ambient temperature is higher than 32℃,
the cooling efficiency will go down quickly and the compressor might be damaged or its service life might
be shorter if the ambient temperature exceeds 32℃for a long time. Therefore, we advise you install an
air-conditioner in the room of the product.)
6.3.3 A single freezer shall be equipped with an independent socket and the maximum current borne by
the power socket shall exceed 16A and the socket shall be grounded reliably.
6.3.4 When you switch on the freezer, firstly turn on the battery switch in the electric control cabinet of
the freezer, then the main power switch. If you want to shut down the freezer for a long time, please
switch off the power supply and then turn off the switch.
6.3.5 The door of the low-temperature freezer shall not be opened over 1min. and the icy water on the
sealing strip of the door shall be dried and cleaned to ensure the good sealing effect.
6.3.6 In order to prolong the service life of the equipment and reduce its energy consumption, we advise
you set its optimal temperature between -50℃and -80℃when you use it, on the premise that the
safety of preserved goods is ensured.
6.3.7 This product is used for preserving goods at low temperature but not for the quick-freezing purpose.
It shall not be used for quick-freezing a lot of goods or large-volume liquid goods forcefully.
6.3.8 If the machine does not cool down after power is on for 2-3 hours, please switch off the power
supply and contact Nuaire technical support as soon as possible.
6.3.9 In case of an alarm failure or other failures, please clear the failure according to the instruction on
the display panel. If there is no instruction or the failure cannot be cleared, please do not disassemble
the freezer by yourself. Please contact after-sales service in time and ask professional maintainers to
help you clear the failure.
Sensor
failure
alarm

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6.4 Failure Code Inquiry
1) When the machine detects that the result of the condenser temperature minus the ambient
temperature is ≥13℃(for 5min. continuously), the “hot condenser” indicator turns on and the machine
makes the relevant silence alarm. After the power supply is on, the indicator does not turn on and the
machine does not make a silence alarm in 3 hours.
2) When the sensor has a failure, the indicator of the “sensor failure” turns on;
3) When the main sensor has a failure, the failure code “E2” of the main sensor and the actual
temperature are displayed alternatively on the display panel.
4) When the condenser sensor has a failure, the failure code “E1” of the main sensor and the actual
temperature are displayed alternatively on the display panel.
5) When the ambient temperature sensor has a failure, the failure code “E0” of the main sensor and the
actual temperature are displayed alternatively on the display panel.
6) When the heat exchanger sensor has a failure, the actual temperature and the failure code “E3” of the
heat exchanger sensor display alternatively on the display panel. When you select -86 and “E3” appears,
after you press the button for clearing the silence alarm for 5 seconds, “E3” disappears. After “E3”
displays, after the high temperature compressor is started, the low temperature compressor will start
with a 1 minute. delay.
Inward main sensor E2
Ambient
temperature sensor
failure E0
Condenser sensor E1

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7) When the temperature detected by the heat exchanger sensor is ≥90℃, the alarm displays E4.
Remark: (If the product has no heat exchanger sensor from -25℃to -50℃, failures E3 and E4 will not
happen to it.)
(If the product has an independent backup system, failures E0, E1, E3 and E4 will not happen to it.)
Alternative display time: the actual temperature is displayed for 6s and the failure code is displayed for 2
seconds.
6.5 Probe resistance changes with the change of the temperature (probe type: NTC,
mainly for ambient temperature sensor, condenser temperature sensor and heat
exchanger sensor)
Temperature
(
℃
)
Resistance
(KΩ)
Temperature
(
℃
)
Resistance
(KΩ)
Temperature
(
℃
)
Resistance
(KΩ)
Temperature
(
℃
)
Resistance
(KΩ)
-40 63.3 -19 17.8 2 5.8 23 2.1
-39 59.4 -18 16.8 3 5.5 24 2.0
-38 55.8 -17 15.9 4 5.2 25 1.9
-37 52.3 -16 15.0 5 5.0 26 1.8
-36 49.2 -15 14.2 6 4.7 27 1.8
-35 46.2 -14 13.4 7 4.5 28 1.7
-34 43.4 -13 12.7 8 4.3 29 1.6
-33 40.8 -12 12.0 9 4.1 30 1.5
-32 38.4 -11 11.4 10 3.9 31 1.5
-31 36.1 -10 10.8 11 3.7 32 1.4
-30 34.0 -9 10.2 12 3.5 33 1.4
-29 32.0 -8 9.7 13 3.4 34 1.3
-28 30.1 -7 9.2 14 3.2 35 1.2
-27 28.4 -6 8.7 15 3.1 36 1.2
-26 26.7 -5 8.3 16 2.9 37 1.1
-25 25.2 -4 7.8 17 2.8 38 1.1
-24
23.8
-3
7.4
18
2.7
39
1.0
-23 22.4 -2 7.1 19 2.5 40 1.0
-22 21.2 -1 6.7 20 2.4 41 1.0
-21 20.0 0 6.4 21 2.3 42 0.9
-20 18.9 1 6.1 22 2.2 43 0.9
Probe resistance changes with the temperature change (probe type: PT100, mainly
for the temperature sensor in the freezer)
The heat exchanger
probe foams at the
bottom inside the
freezer.
E3 at the terminal of
the heat exchanger
sensor

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温度
（℃）
阻值
（Ω）
温度
（℃）
阻值
（Ω）
温度
（℃）
阻值
（Ω）
-140 43.9 -70 72.3 0100.0
-130 48.0 -60 76.3 10 103.9
-120 52.1 -50 80.3 20 107.8
-110 56.2 -40 84.3 30 111.7
-100 60.3 -30 88.2 40 115.5
-90 64.3 -20 92.2 50 119.4
-80 68.3 -10 96.1 60 123.2
Tempera
ture (℃)
Resistan
ce (Ω)
Resistan
ce (Ω)
Resistan
ce (Ω)
Tempera
ture (℃)
Tempera
ture (℃)

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7.Main Technical Parameters of the Product
7.1 Technical Parameter Table
Model
NU-99578
JE
NU-99578
JG
NU-99578
JGA
NU-99728
JE
NU-99728
JG
NU-99338
JE
NU-99338
JG
NU-99338
JGA
Technical Data
Cabinet Type
Single Door, Upright
Climate Class
N
Controller
Micro-processor control
Display
LED Display with 1 C increment
Temp Sensor
PT100
Parameters
Capacity(L)
578
728
338
Power Suppiy
（
V/Hz
）
220~240
50
208~230
60
115
60
220~240
50
208~230
60
220~240
50
208~230
60
115
60
Power
（
W
）
750
1000
1000
1000
1000
650
1000
1000
Electrical Cueernt
6
9
18
10
10
5
7.5
12
Interior
Dimension
（
W*D*H
）
620*716*1310 (mm)
24.4*28.2*51.6 (in)
766*716*1310 (mm)
30.2*28.2*51.6 (in)
465*630*1165 (mm)
18.3*24.8*45.9 (in)
Exterior
Dimension
（
W*D*H
）
895*980*1960 (mm)
35.2*38.6*77.2 (in)
1041*980*1980 (mm)
41.0*38.6*78.0 (in)
812*893*1846 (mm)
32.0*35.2*72.7 (in)
Net/Gross Weight
300/330 (kg)
661/728 (lb)
345/380 (kg)
761/838 (lb)
238/278 (kg)
525/613 (lb)
Material
External Material Zinc-coated steel
Internal Material Zinc-coated steel
Heat preservation
Material
Composite Insulation with VIP and fluoride free PU foam
Door Thickness
90 (mm)
3.54 (in)
90 (mm)
3.54 (in)
Enclosure
Thickness
90 (mm)
3.54 (in)
130 (mm)
5.12 (in)
Outside door
sealing structure
Four silicone gaskets Four silicone gaskets
Inside door
sealing structure
Independent door with single silicone gasket
Independent door with single
silicone gasket
door lock buckle Y/1
Product
accessories
Shelves/Inner
Doors
3/4 3/2
Shelves(W*D)
602*680 (mm)
23.7*26.7 (in)
750*680 (mm)
29.5*26.7 (in)
449*595 (mm)
17.7*23.4 (in)
Castor / Test Hole 4/2 4/2
Compressor type
/ quantity
Hermetically sealed X 2
Compressor
Model
SC21CNX.2
NLE12.6CN
L(2018.5.1)
SC21CN
LX.2(20
8~230V/
60Hz)
SC18CM
X.2(115
V/60Hz)
SC21CN
X.2(220~
240V/50
Hz)
SC21CN
LX.2(208
~230V/6
0Hz)
SC21CN
X.2
NLE12.6
CNL(20
18.5.1)
SC21CN
X.2(208~
230V/60
Hz)
NLE11CN
L(115V/60
Hz)
Refrigerant HC-Free/H-R290 L-R290 R170（Refer to 8.5.4 for actual charge）

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Model NU-99828JE
NU-99828JG
Technical Data
Cabinet Type
Single door, upright
Climate Class
N
Controller
Microprocessor control
Display
LED Display with 1 C increment
Temp Sensor
PT100
Parameters
Capacity(L)
828
Power Supply
（
V/Hz
）
220~240V/50Hz
208~230V/60Hz
Power（W）1000 1000
Electrical Current 10 10
Interior Dimension
（W*D*H）
870*716*1310 (mm)
34.3*28.2*51.6 (in)
Exterior Dimension
（W*D*H）
1145*980*1980 (mm)
45.1*38.6*78.0 (in)
Net/Gross Weight
380/410 (kg)
838/904 (lb)
Material
External Material Zinc-coated steel
Internal Material Zinc-coated steel
Heat preservation Material
Composite Insulation with VIP and fluoride free PU foam
Door Thickness
90 (mm)
3.54 (in)
Enclosure Thickness
90 (mm)
3.54 (in)
Outside door sealing
structure
Four silicone gaskets
Inside door sealing
structure
Single silicone gasket on independent door
door lock buckle Y/1
Product Accessories
Shelves/Inner Doors 3/4
Shelves(W*D)
854*680 (mm)
33.6*26.8 (in)
Castor / Test Hole 4/2
Compressor type / quantity Hermetically sealed compressor X 2
Compressor Model SC21CNX.2(220~240V/50Hz) SC21CNLX.2(208~230V/60Hz)
Refrigerant HC-Free/H-R290 L-R290 R170（Refer to 8.5.4 for actual charge）

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Model NU-99420JE
NU-99420JG
Technical Data
Cabinet Type Single door, chest
Climate Class N
Controller Microprocessor control
Display LED Display with 1 C increment
Temp Sensor PT100
Parameters
Capacity(L) 420
Power Supply
（
V/Hz
）
220~240V/50Hz
208~230V/60Hz
Power（W）1000 1000
Electrical Current 7.5 7.5
Interior Dimension（W*D*H）1367*462*652 (mm)
53.8*18.2*25.7 (in)
Exterior Dimension（W*D*H）2130*870*1020 (mm)
83.9*34.3*40.2 (in)
Net/Gross Weight
310/357 (kg)
683/787 (lb)
Material
External Material Zinc-coated steel
Internal Material Stainless steel
Heat preservation Material
Composite Insulation with VIP and fluoride free PU foam
Door Thickness
100 (mm)
3.94 (in)
Enclosure Thickness
140 (mm)
5.51 (in)
Outside door sealing structure
Single silicone gasket
Inside door sealing structure
/
door lock buckle Y/1
Product Accessories
Shelves/Inner Doors 0/3
Shelves(W*D) /
Castor / Test Hole 4/1
Compressor type / brand /
quantity
Hermetically sealed compressor X 2
Compressor Model SC21CNX.2(220~240V/50Hz) SC21CNlX.2(208~230V/60Hz)
Refrigerant HC-Free/H-R290 L-R290 R170（Refer to 8.5.4 for actual charge）