nvent Spectracool N28 User manual

© 2022 nVent 89215756
Rev. A P/N 89215756
SPECTRACOOL
Air Conditioner
n28 Model
INSTRUCTION MANUAL

© 2022 nVent 89215756
- 2 -
TABLE OF CONTENTS
Warranty and Return Policy ................................................................................................................................................................................... 3
RECEIVING THE AIR CONDITIONER ..................................................................................................................................................................... 3
HANDLING AND TESTING THE AIR CONDITIONER ............................................................................................................................................ 3
HOW TO READ MODEL NUMBERS ....................................................................................................................................................................... 3
For cooling (75-100 F range):........................................................................................................................................................................................... 4
For heating (55-65 F range):............................................................................................................................................................................................. 4
TECHNICAL INFORMATION .................................................................................................................................................................................. 4
Sequence of Operation.............................................................................................................................................................................................................. 4
Heating............................................................................................................................................................................................................................... 4
Cooling ............................................................................................................................................................................................................................... 4
Standard and Optional Component Operation........................................................................................................................................................................ 4
Thermostat ........................................................................................................................................................................................................................ 4
Remote Access Control (optional) .................................................................................................................................................................................. 4
Head Pressure Control (optional).................................................................................................................................................................................... 4
115V/230V to 10V Transformer (optional)..................................................................................................................................................................... 4
115V/230V to 24V Transformer and Relay (optional) ................................................................................................................................................... 4
Schematics and Wiring Diagrams for Thermostat Control .................................................................................................................................................... 5
Generic 115V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................... 5
Generic 230V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................... 5
Generic 460V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................... 6
Generic 115V 1-Phase Wire Diagram (actual unit options may vary)........................................................................................................................... 7
Generic 230V 1-Phase Wire Diagram (actual unit options may vary)........................................................................................................................... 8
Generic 460V 1-Phase Wire Diagram (actual unit options may vary)........................................................................................................................... 9
DIMENSIONAL DRAWING.................................................................................................................................................................................... 10
With Thermostats..................................................................................................................................................................................................................... 10
INSTALLATION INSTRUCTIONS.......................................................................................................................................................................... 11
DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)......................................................................................................................................... 12
Overview.................................................................................................................................................................................................................................... 12
ENERGIZING THE CONTROLLER............................................................................................................................................................................................ 12
CONTROL STATUS INDICATION............................................................................................................................................................................................. 12
DISPLAYING AND CHANGING PROGRAM Settings.............................................................................................................................................................. 15
To view or access the settings....................................................................................................................................................................................... 15
Heat/Cool Operating Parameters ........................................................................................................................................................................................... 15
Alarm Parameters.................................................................................................................................................................................................................... 15
DISPLAYING TEMPERATURE DATA ON SCREEN.................................................................................................................................................................. 17
COMPRESSOR RESTART TIME DELAY................................................................................................................................................................................... 17
ALARM OUTPUT CONTACT .................................................................................................................................................................................................... 17
ALARM INPUT CONNECTION ................................................................................................................................................................................................. 17
PRIMARY-SECONDARY (PS) MODE ....................................................................................................................................................................................... 18
Connecting units together in Primary/Secondary mode...................................................................................................................................................... 18
Connecting units together in Lead/Lag mode....................................................................................................................................................................... 19
AIR CONDITIONER UNIT REMOTE COMMUNICATION FEATURES...................................................................................................................................... 20
USB COMMUNICATION .................................................................................................................................................................................................. 20
ETHERNET COMMUNICATION ...................................................................................................................................................................................... 20
USING HOFFMAN PC INTERFACE TOOL ............................................................................................................................................................................... 21
USB COMMUNICATION MODE ...................................................................................................................................................................................... 21
USB COMMUNICATION MODE ...................................................................................................................................................................................... 22
ETHERNET COMMUNICATION MODE .......................................................................................................................................................................... 23
REMOTE ACCESS CONTROL PIN-OUT................................................................................................................................................................................... 24
Schematics and Wiring Diagrams for Remote Access Control........................................................................................................................ 25
Generic 115V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................. 25
Generic 230V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................. 25
Generic 460V 1-Phase Schematic (actual unit options may vary) ............................................................................................................................. 26
Generic 115V 1-Phase Wire Diagram for Remote Access Control (actualunit options may vary) ......................................................................... 27
Generic 230V 1-Phase Wire Diagram for Remote Access Control (actualunit options may vary) ......................................................................... 28
Generic 460V 1-Phase Wire Diagram for Remote Access Control (actualunit options may vary) ......................................................................... 29
DIMENSIONAL DRAWING.................................................................................................................................................................................... 30
With Remote Access Control.................................................................................................................................................................................................. 30
INSTALLATION INSTRUCTIONS WITH REMOTE ACCESS CONTROL ............................................................................................................. 31
MAINTENANCE .................................................................................................................................................................................................... 32
Compressor .............................................................................................................................................................................................................................. 32
Inlet Air Filter............................................................................................................................................................................................................................. 32
How To Remove, Clean or Install a New Inlet Air Filter......................................................................................................................................................... 32
Condenser and Evaporator Air Movers .................................................................................................................................................................................. 33
Refrigerant Loss....................................................................................................................................................................................................................... 33
Refrigerant Properties Chart (R134a)..................................................................................................................................................................................... 33
Unit Characteristics.................................................................................................................................................................................................................. 34
Functional Data ........................................................................................................................................................................................................................ 34
SERVICE DATA ...................................................................................................................................................................................................... 35
Components List...................................................................................................................................................................................................................... 35
N280416GXXX Pressure Tables............................................................................................................................................................................................. 36
N280426GXXX Pressure Tables............................................................................................................................................................................................. 37
N280446GXXX Pressure Tables............................................................................................................................................................................................. 38
F-GAS INFORMATION .......................................................................................................................................................................................... 38
TROUBLE SHOOTING........................................................................................................................................................................................... 40
Basic Air Conditioning Trouble Shooting Check List - Thermostat Version........................................................................................................................ 40
Symptoms and Possible Causes - Thermostat Version....................................................................................................................................................... 41
Basic Air Conditioning Trouble Shooting Check List - Remote Access Control Version ................................................................................................... 42
Symptoms and Possible Causes - Remote Access Control Version................................................................................................................................... 43

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NOTE: Some of the information in this manual may not apply if a special unit was ordered. If
additional drawings for a special unit are necessary, they have been inserted. Contact Pentair
Equipment Protection if further information is required.
WARRANTY AND RETURN POLICY
https://hoffman.nvent.com/en/hoffman/warranty-information
RECEIVING THE AIR CONDITIONER
Inspect the air conditioner. Check for concealed damage that may have occurred during shipment. Look for dents,
scratches, loose assemblies, evidence of oil, etc. Damage evident upon receipt should be noted on the freight bill.
Damage should be brought to the attention of the delivering carrier -- NOT to nVent Equipment Protection -- within
15 days of delivery. Save the carton and packing material and request an inspection. Then le a claim with the
delivering carrier.
nVent Equipment Protection cannot accept responsibility for freight damages; however, we will assist you in any
way possible.
Do not attempt to operate the air conditioner while it is horizontal
or on its side, back or front. The refrigeration compressor is lled
with lubricating oil. This will cause permanent damage to the air
conditioner and also voids the warranty.
CAUTION
HANDLING AND TESTING THE AIR CONDITIONER
If the air conditioner has been in a horizontal position, be certain it is placed in an upright, vertical or mounting
position for a minimum of ve (5) minutes before operating.
TEST FOR FUNCTIONALITY BEFORE MOUNTING THE AIR CONDITIONER TO THE ENCLOSURE.
Refer to the nameplate for proper electrical current requirements, and then wire the unit to a properly grounded
power supply using copper conductors only. Power supply wiring should be restrained after eld installation to
ensure no contact with internal fan. Minimum circuit ampacity should be at least 125% of the amperage shown
on the unit nameplate. No other equipment should be connected to this circuit to prevent overloading
Immediately after applying power, the evaporator blower (enclosure air) should start running. Operate the
air conditioner with the compressor running for ve (5) to ten (10) minutes. You will need to set the cooling
thermostat or controller setpoint below the ambient temperature to operate the compressor.
Condenser air temperatures should be warmer than normal room temperatures within a few minutes after the
condenser impellers start.
See Sequence of Operation on page 4 for specics on how the unit operates when powered up.
HOW TO READ MODEL NUMBERS
N28 04 2 6 G150
12345
1. Identies the type/family of air conditioner and the approximate height (i.e. G28 = Global family
about 28 inch high).
2. This is the air conditioner’s listed capacity in BTU/Hr. at rated conditions. (i.e. 06=6,000 BTU/Hr. at
131/131 F)
3. 1 = 115 Volt, 2 = 230 Volt, 4 = 460 Volt.
4. 6 = 50/60 Hz or 60 Hz only.
5. Unique set of numbers for each air conditioner which identies the accessories on a model.

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TECHNICAL INFORMATION
SEQUENCE OF OPERATION
The air conditioner comes standard with two internally mounted thermostats or remote access control. There are
two modes of operation; heating and cooling. During heating and cooling modes the evaporator fan will be running.
HEATING
When the enclosure temperature is below the heating thermostat setpoint, power is applied to the
heaters. When the enclosure temperature is 10 degrees above the setpoint the heater is powered off.
COOLING
When the enclosure temperature is above the cooling thermostat setpoint, power is applied through the
thermostat. The compressor is then energized either directly or through a contactor if unit requires one.
The condenser impellers will start immediately if the unit is not equipped with an optional head pressure
control switch. If the unit is equipped with an optional head pressure control switch, the condenser
impellers will start once the refrigerant pressure reaches the setting of the switch. Component specic
information is listed below.
Operating the air conditioner below the minimum ambient temperature or above the maximum ambient
temperatures indicated on the nameplate voids all warranties. DO NOT set the enclosure thermostat to a
temperature lower than 70 F. Doing so can increase the likelihood of frost buildup on the evaporator coil.
The moisture that the enclosure air can contain is limited. If moisture ows from the drain tube
continuously this can only mean that ambient air is entering the enclosure. Be aware that frequent
opening of the enclosure’s door admits humid air that the air conditioner must then dehumidify.
STANDARD AND OPTIONAL COMPONENT OPERATION
THERMOSTAT
The standard G28 air conditioner uses our standard 10-1061-16 thermostat. The thermostat setpoint
equals the temperature that the air conditioner turns off. The thermostat has a 10 F differential from
setpoint until it calls for cooling or heating. An example of operation is shown below.
FOR COOLING (75-100 F RANGE):
• Thermostat setpoint = 80 F
• Cooling turns on at 90 F
• Cooling turns off at 80 F
FOR HEATING (55-65 F RANGE):
• Thermostat setpoint = 55 F
• Heating turns on at 55 F
• Heating turns off at 65 F
NOTE: For testing purposes only, the thermostat stop screw may be removed (on units so
equipped) to allow settings below 70 F. After testing, replace the stop screw and verify that the
thermostat cannot be set below 70 F. Extended operation below 70 F can cause coil freeze ups
resulting in reduced load and/or unit damage.
REMOTE ACCESS CONTROL (OPTIONAL)
See DIGITAL THERMOSTAT CONTROLLER (OPTIONAL) on page 12
HEAD PRESSURE CONTROL (OPTIONAL)
Unit is set at the factory, no adjustment necessary.
At a saturated condenser temperature of 82 F (95 psig), the condenser fans will power off. At a saturated
condenser temperature of 105 F (165 psig), the condenser fans will power on.
115V/230V TO 10V TRANSFORMER (OPTIONAL)
This transformer powers the thermal display on thermostat controlled units only.
115V/230V TO 24V TRANSFORMER AND RELAY (OPTIONAL)
The transformer and relay are used to operate the condenser blower and compressor by using a customer
supplied, remote mounted door switch. This is not a safety door switch, but rather, only helps to reduce
condensation at the evaporator coil if the door is opened. The unit will remain electried when the door
switch is operated with the evaporator fan continuing to operate, and potentially, if temperatures are low
enough, the heater may continue to operate on outdoor models.

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SCHEMATICS AND WIRING DIAGRAMS FOR THERMOSTAT CONTROL
GENERIC 115V 1-PHASE SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)
89074302
GENERIC 230V 1-PHASE SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 460V 1-PHASE SCHEMATIC (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 115V 1-PHASE WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)
HEATER
BLK12
AMB.
ENC.
HPC
OR C/E
(OPTIONAL)
BLK20
T-STAT
COOLING
RED13
BLK
BLK
BRN
GRN/YEL
IMPELLER
AMBIENT BLU
BLK
BLU19
BLK12
YEL10
BLK11
WHT7
RED13
BLU9
BRN8
BLK20
HEATING
T-STAT
RED30
BRN26
13
MALF
SWITCH
(OPTIONAL)
2
YEL(NO) RED(COM) BLU(NC)
BLU29
COMP HTR
(OPTIONAL)
(OPTIONAL)
SUPPRESSOR
THERMAL DISPLAY (OPT.)
TO THERMAL
115(230) V
10 V
DISPLAY
WHT41
BLK40
DOOR SWITCH (OPT.)
RED62
T'FORMER
BLK60
WHT61
YEL65
RELAY
0
1
4
8
2
6
YEL10
YEL10 OR
YEL65
WHT63 WHT64
BLK27
BLK28
SWITCHES
LIMIT
GRN/YEL21
POWER
BLOCK
1
2
WHT15
FAN
ENCLOSURE
BLK14
BLK14
WHT7
BLK11
3
R
START CAPACITOR
BLK23
C
BLK 115V / WHT 230V BLK 115V / WHT 230V
4
BLU19
BLU21
BLU22
5
43
6
43
6
CUSTOMER
SWITCH
TO
COMPRESSOR
0.L.
S
89073631

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GENERIC 230V 1-PHASE WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)

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GENERIC 460V 1-PHASE WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)

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DIMENSIONAL DRAWING
WITH THERMOSTATS
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INSTALLATION INSTRUCTIONS
1. Inspect the air conditioner and verify correct functionality before mounting the air conditioner. See
HANDLING AND TESTING THE AIR CONDITIONER on page 3.
2. Using the mounting gasket kit provided with the unit, install gaskets to the air conditioner, see
Figure 1.
3. Mount air conditioner on enclosure taking care not to damage the mounting gasket. The
mounting gasket is the seal between the air conditioner and the enclosure. Avoid dragging the air
conditioner on the enclosure with the mounting gasket attached as this could cause rips or tears
in the gasket and risk losing the water tight seal.
4. To avoid cross-threading mounting inserts, start bolts by hand before tightening with a wrench or
ratchet driver.
5. Allow unit to remain upright for a minimum of ve (5) minutes before starting. CAUTION! Air
conditioner must be in upright position during operation.
6. Refer to the nameplate for electrical requirements. Wire the unit to a properly grounded power
supply. Electrical circuit should be fused with slow blow or HACR circuit breaker.
7. Some air conditioners require a remote mounted thermostat. Wire the thermostat outputs to the
appropriate terminals on the 24 VAC terminal strip by noting the locations on the correct wiring
diagram.
8. Set thermostat for required cabinet temperature. Refer to Sequence of Operation on page 4 for
thermostat adjustment and operation.
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Surface Mount
Figure 1
Cut-out Drawing

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DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)
OVERVIEW
The digital thermostat (controller) is a parametric controller for the complete management of air conditioners.
All settings are pre-programmed at the factory. Cooling/heating setpoint, cooling/heating differential and high/
low temperature setpoint are designed to be adjustable by the operator. All alarms are outputted through the
alarm relay. In addition, if Hoffman network card (Remote Access Control (RAC) Module) is used the parameters
that state above and alarms are accessible remotely through Ethernet connection utilizing SNMP, Modbus TCP,
EtherNet/IP, and Pronet protocol . A USB connection from the network card is also provided with accessibility
to the digital thermostat controller utilizing Modbus RTU and RS-845 serial bus. In addition, the USB connection
is also used to read the network information from the Hoffman network card and temperature setpoints and
alarm from the controller. Note that Hoffman network card (RAC module) is acting as a gateway to the digital
thermostat where temperature setpoints and alarm can be viewed and/or changed remotely.
Note: nVent Hoffman network card (RAC module) is an optional accessory, therefore, some of
the air conditioners ship without the network card but it is upgradable upon request.
ENERGIZING THE CONTROLLER
The digital controller is wired and programmed at the factory to operate when power is applied to the air
conditioner. In normal condition, the evap fan starts operating after the completion of the self-evaluation which
is less than 30 seconds and fan icon should be illuminated along with the inlet and outlet temperature data (if an
option outlet temperature sensor is installed).
CONTROL STATUS INDICATION
The display has numerous symbols to indicate the various controller functions such as cooling, heating, alarming,
evaporator fan, and heating. Indicators (icons) are steady illuminated on screen when active.
Figure 2
Display

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KEYPAD
SYMBOL COLOR ICON INDICATION ICON STATUS
Red Alarm - active when alarm is detected Flashing when alarm is detected
White
Keypad Select – access to passcode , hold 5 sec
to turn unit ON/OFF, parameter menu, parameter
setting, write or save to EEPROM, and hold for
3sec to return to main screen
ON
White Keypad Up – navigate to previous parameter and
increasing parameter variable ON only when reviewing parameters
White Keypad Down – navigate to next parameter and decreasing parameter variable, all inputs, unit
status. ON
MAIN FIELD
SYMBOL COLOR ICON INDICATION ICON STATUS
°C White When operating temperature in degrees Celsius ON
°F White When operating temperature in degrees of Fahrenheit ON
Main Field
Line 1 White Display inlet temperature ON
Main Field
Line 2 Orange
1. Display outlet temperature in standalone
mode if outlet sensor is present
2. Displays device ID for primary-secondary
mode up to 10 units, 1:10 … 10:10 or lead-
lag mode up to 2 units, 1:2… 2:2
ON
ICONS
SYMBOL COLOR ICON INDICATION ICON STATUS
White Compressor Running
• Flashing while waiting for
compressor to turn ON
• Steady ON while compressor
is running
White Evaporator Running ON
White Electric heater ON ON
White Primary and/or lead controller ON
White Freeze control Compressor and Condenser fan OFF
while illuminated
White Power ON ON

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DISPLAYING AND CHANGING PROGRAM SETTINGS
TO VIEW OR ACCESS THE SETTINGS
TO ACCESS FOLDER MENUS:
1. Press button to display passcode screen, the screen displays PSd on line 1 and 0000 on line 2.
2. Press button to access to passcode , the rst digit of 0000 is ashing and press 3 more times
until the last digit of 0000 ashes.
3. Press arrow two times to change the 0 to 2. Press for access to folder menus.
Note: to exit the security level to the main screen wait one minute with no action or Press
arrow until LOG Out message displays, then press button.
TO CHANGE A PARAMETER SETTING
1. Once in the folder menu navigate to the desired setting to be changed using the arrow to scroll
and button to access a menu or parameter.
2. To change a parameter Press button and parameter value will begin to ash.
3. Press /arrow to the desire value.
4. Press button to save the setting and the screen will revert to the parameter mnemonic.
Note: if button is not pressed, the new setpoint is not saved.
To exit the parameter settings to the main screen wait one minute with no action or Press arrow
few times until ESC displays, then press button to return to UoF screen. From the UoF screen
Press arrow few times until LOG Out message displays, then press button to return to the
main screen.
Selecting ESC returns to folder menu.
Selecting LOG out returns to main screen.
HEAT/COOL OPERATING PARAMETERS
Mnemonic
Parameter Description Default Value Range
CSt1Cooling setpoint 80 F 72 F to 120 F
Cd (Cd1)1Cooling differential 7 F 2 F to 25 F
Cd24Cooling differential 2 15 F
HSt2 3 Heating setpoint 50 F 45 F to 60 F
Hd3Heating differential 7 F 2 F to 25 F
1 Compressor or cooling turns ON at CSt + Cd and OFF at CSt
2 Heater or heating turns ON at HSt and OFF at HSt + Hd
3 Heating mode is only applied to a unit with heater option
4 Cooling differential 2 is only applied to 2-stage compressor and lead-lag application
ALARM PARAMETERS
Mnemonic Para Description Default value
Ht High temperature alarm setpoint 125 F
Lt Low temperature alarm setpoint 40 F
dO Door open alarm setting NC
ArOP Alarm relay output NO
NOTES: (4) The alarm relay output logic is designed to be congurable

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VIEW ALARMS
Alarms may be viewed when the alerting icon is ashing.
1. On the main screen, press the alerting icon button
2. The screen displays the most recent or newest alarm where the alarm code display on line 1 and
the alerting icon is now in steady
3. Press arrow to view next alarm if there are more than one
4. Press arrow to display ESC, then press button to return to the main screen
VIEW THE ALARMS IN THE ALARM HISTORY FOLDER
1. Follow instructions above to enter the passcode and open the alarm history folder (AHiF).
2. Press button to access to the alarm history.
3. Press arrow to display the mnemonic alarm on line 1 and time, month, and day display on line
2. For example, low temp alarm (Lt) displays on line 1 and 09:24 and 0706 display on line 2 in
sequence. Note that the time, and date recorded in the alarm history is based on the local real-
time-clock if congured after installation.
4. Press arrow to view next alarm. The controller is able to retain up to 25 events
5. Press arrow until the screen displays ESC, then press button to return to the main screen
or if no action for longer than 60 seconds the screen will be automatically revert to the main
screen.
NOTE: if no alarms are present then only ESC will be displayed in the folder.
There are seven possible alarms (non-latching) detectable by the controller and are indicated on
the controller display. All alarms are accessible locally. If a Hoffman network card (RAC module) is
used, alarms are also accessible remotely through the Ethernet and USB connection.
Mnemonic Alarm Description Cause Result Alarm Relay Output
dO Door open alarm Enclosure door opens
or not properly close Compressor and evap fan turn OFF in duration of alarm Closed
S1F Inlet temperature
sensor fault Inlet temp probe failed
No effect on function,
controller continue operating
as normal using outlet sensor
with setpoint of 50 F
Closed
S2F Outlet temperature
sensor fault Outlet temp probe failed No effect on function but loss freeze protection Closed
LA Malfunction alarm MALF high pressure
switch opens No effect on function Closed
Ht High temp warning Enclosure air exceeds high temp alarm
setpoint No effect on function Closed
Lt Low temp warning Enclosure air drops below low temp alarm
setpoint No effect on function -
FA Frost alarm Evaporator coil freezes
Compressor and condenser
fan turns OFF for the duration
of alarm. Alarm clears when
the outlet temperature sensor
reaches 59 F
Closed

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TO RESET THE ALARMS IN ALARM HISTORY FOLDER
The controller is designed with ability to reset or clear the alarm history
6. Follow instructions above to enter the passcode and open the reset folder (rStF).
7. The screen displays rSAL on line 2 and nO on line 1, press button the nO is ashing
8. Press arrow to change nO to YeS, then press button reset the alarms. The screen ashes
once and returns to rSAL with nO one line 2
9. Press arrow to navigate to ESC, then press to returns to rStF screen.
10. Press arrow to navigate to LOG Out, then press button to return to the main screen or if no
action for longer than 60 seconds the screen will be automatically reverted to the main screen.
TO RESET PARAMETERS TO FACTORY DEFAULT
This option is ONLY applied if the operator wants to reset all control parameters back to factory default.
1. Follow instructions above to enter the passcode and open the reset folder (rStF).
2. The screen displays rSAL, press arrow to navigate to rSPA and then press button
3. The screen displays rSPA one line 1 and the word nO on line 2 in steady state, press button and
then the word nO is ashing and ready to change
4. Press arrow to change nO to YES. Press button the screen displays PSd with 0000 on line 2
5. Press button to enter to passcode. Press button few times until the last digit of 0000 ashing
6. Press arrow to change 0 to 2, press button to authorize the reset of the parameters
7. The screen returns to rSPA screen in steady state.
8. Press arrow to navigate to ESC, then press to returns to rStF screen.
9. Press arrow to navigate to LOG Out, then press button to return to the main screen or if no
action for longer than 60 seconds the screen will be automatically reverted to the main screen.
DISPLAYING TEMPERATURE DATA ON SCREEN
There are two temperature probes in the air conditioner where one is reading the enclosure air temperature
incoming to the air conditioner and other is reading the cooled air leaving the air conditioner and entering the
enclosure. Both temperature data are displayed on the screen where line 1 is the reading of the inlet temperature
and line 2 is the reading of the outlet temperature.
COMPRESSOR RESTART TIME DELAY
A factory set 3 minute (180 seconds) restart delay exists to reduce residual back pressure before allowing
the compressor to restart. The compressor will stay off for the entire restart duration after the compressor is
disabled. A ashing compressor icon on the display indicating that the unit is in a compressor restart delay
mode while calling for cooling or waiting for compressor to turn ON.
ALARM OUTPUT CONTACT
The digital controller has a normally open dry contact alarm output with a resistive load rating of 250VAC @ 5
amps max. The two yellow 18 AWG wires located at the back of the air conditioner provide a connection to this
output. Note: do not apply power to this normally open dry contact (two yellow 18 AWG wire). This alarm relay
output is congurable and provides user with the ability to change the conguration to support their external
device. Parameter C21 controls the alarm relay output logic and can be accessed through security code “0022” in
the PArF folder.
Para Description Conguration
C21 Alarm relay output logic 0 = normally open (NO) – factory default
1 = normally closed (NC)
ALARM INPUT CONNECTION
The digital controller can accept a dry contact/switch input via the two 18 AWG white wires located at the back
of the air conditioner. This input is associated with the controller display alarm mnemonic dO (door open). To use
this feature, remove the splice connector, and connect the two white wires to customer supplied enclosure door
switch in its place. Note: do NOT apply power to this dry contact input.

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PRIMARY-SECONDARY (PS) MODE
Note: during normal operation, in both the primary-secondary (PS) and lead-lag (LL) operating modes,
line 2 displays the device ID, not the outlet temperature. The outlet temperature can be viewed on line
1 by pressing arrow.
Primary-secondary (PS) mode shares the same hardware and source code as standalone mode, but offers more
functionality and features. The controller ships from the factory in Standalone Mode. PS mode is congured
manually in the eld after the installation. This option allows the user to operate the air conditioner in a group
network with up to 10 units. To support PS mode, three parameters, H01, H02, and H03 need to be congured.
H01 species the operating mode, H02 species the device ID, and H03 species the total number of the units in
the group network.
Before conguring to operate in PS mode, the user should understand the functionality of the PS mode.
1. In the PS mode, all units operate off the cooling/heating setpoint and differential of the primary
unit. The system prevents setpoint changes from secondary units.
2. The primary unit monitors the enclosure temperatures of all the units and manages the ON/OFF
status of cooling and heating based on the unit reporting the highest temperature.
3. When cooling is initiated the primary unit energizes rst. Secondary units are energized
sequentially at 10 second intervals. When heating is initiated all units turn on heat together. When
cooling or heating is satised all units turn off together.
4. If the number of units communicating on the network doesn’t match the value in H03 then
the primary unit will display alarm LC, and the secondary units will display alarm LC1 until the
communication re-established.
5. Any unit that loses communication with the primary unit will enter standalone mode and continue
operating based on its own temperature probe until communication is re-established.
6. All temperature setpoints and alarms can be viewed remotely if one of the ACUs is equipped with
Hoffman network card (RAC module).
7. Best recommendation is to congure the ACU that has Hoffman network card to be the primary
one.
CONNECTING UNITS TOGETHER IN PRIMARY/SECONDARY MODE
Primary - Device ID 1 Secondary - Device ID 2 Secondary - Device ID 3 Secondary - Device ID 10
Figure 3
Primary-secondary network connectivity

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TO CONFIGURE THE CONTROLLER FROM SINGLE MODE TO PS MODE, SIMPLY FOLLOW BELOW
PROCEDURES
1. Before proceeding the PS mode conguration for each controller, make sure that the
communication cable is connected from one ACU to another using a shielded cable with the
shield grounded.
2. Press button to display passcode screen, the screen displays PSd on line 1 and 0000 on line 2.
3. Press button to access to passcode , the rst digit of 0000 is ashing and press 2 more times
until the third digit 0000 ashes. Press arrow two times to change 0to 2, then press button
to move to the last digit 0020
4. Press arrow two times to change the 0 to 2.
5. Press button to access to folder menu and then, the screen displays ALrF
6. Press arrow to navigate to PArF, then press button to access to parameter menu
7. The screen displays C, press arrow to navigate to parameter Hand then, press button to
access to parameter Hmenu
Parameter Description Available Range PS Settings Default
H01 Mode
SA (stand alone)
PS (primary-secondary) SAPS (primary-secondary)
LL (lead-lag)
H02 Device ID 1 up to 10 1 up to H03 1
H03 Total number of the units in
the group network 1 up to 10 2 up to 10 1
8. Set parameter H01 to PS (primary-secondary).
Note that after H01 = PS, the snowflake icon is illuminated and line 2 changes its display
information from outlet temperature to device ID, for example, line 2 displays 01:02 where 01
indicates controller #1 and 02 indicates the total number of the controllers in a group network.
Keep in mind that the snowflake icon only illuminates on primary controller.
9. Set parameter H02 (device ID) to 1 to 10. This device ID will be different for each controller that
is connected. The controller set to 1 will be the primary controller. Use numbers sequentially and
don’t skip using a number.
10. Set parameter H03 (total number of controllers connected) to 1 to 10.
CONNECTING UNITS TOGETHER IN LEAD/LAG MODE
Lead - Device ID 1 Lag - Device ID 2
Figure 4
Lead-Lag network connectivity

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TO CONFIGURE THE CONTROLLER FROM SINGLE MODE TO LL MODE, SIMPLY FOLLOW BELOW
PROCEDURES. PERFORM THIS CONFIGURATION FOR BOTH AIR CONDITIONERS.
1. Before proceeding the LL mode conguration for each controller, make sure that the
communication cable is connected from one ACU to another using a shielded cable with the
shield grounded.
2. Press button to display passcode screen, the screen displays PSd on line 1 and 0000 on line 2.
3. Press button to access to passcode, the rst digit of 0000 is ashing and press 2 more times
until the third digit 0000 ashes. Press arrow two times to change 0to 2, then press button
to move to the last digit 0020.
4. Press arrow two times to change the 0 to 2.
5. Press button to access to folder menu and then, the screen displays ALrF.
6. Press arrow to navigate to PArF, then press button to access to parameter menu.
7. The screen displays C, press arrow to navigate to parameter Hand then, press button to
access to parameter Hmenu.
Parameter Description Available Range LL Settings Default
H01 Mode SA (stand alone) PS (primary-secondary)
LL (lead-lag) LL (lead-lag) SA
H02 Device ID 1 up to 10 1 or 2 1
H03 Total number of the units
in the group network 1 up to 10 2 1
H14 LL strategy selection 0-250 0 (Alternate each cycle)
1-250 (Alternate hours) 0
8. Set parameter H01 to LL (lead-lag).
9. Set parameter H02 (device ID) to 1 for one unit and 2 for the other unit.
10. Set parameter H03 (total number of controllers connected) to 2.
11. Set parameter H14 (LL strategy selection) to 0 to 250. This is the run time in hours before ACU1
and ACU2 will alternate being the lead unit. When set to zero ACU1 and ACU2 will automatically
alternate every cycle.
AIR CONDITIONER UNIT REMOTE COMMUNICATION FEATURES
Air conditioners that include the optional Hoffman network card (RAC module) have remote communication
capabilities utilizing SNMP, Modbus TCP, EtherNet/IP, Pronet Protocol via Ethernet connection, and Modbus
RTU protocol via USB connection. nVent provides Windows interface application software that is available
to download free from nVent support link https://go.nvent.com/remote-access-control-support-center. The
Windows interface application software supports both Ethernet and USB communication.
USB COMMUNICATION
This communication mode allows direct connection from a laptop (or PC) to the air conditioning unit
using a Mini-b USB cable. As stated above, Modbus RTU is used to communicate between the two
devices via USB connection.
ETHERNET COMMUNICATION
This communication mode allows remote connection to the air conditioning unit utilizing SNMP, Modbus
TCP, EtherNet/IP, and Pronet protocol. Customers that use their own software can download an MIB le
for SNMP, EDS or EtherNet/IP Object le for EtherNet/IP, Coil Register le for Modbus TCP, and Data Point
for Pronet.
Note: the Ethernet card (RAC module) has a default IP Address of 192.168.1.2
Both Ethernet and USB communication allow the ability to:
• Read ACU inlet and outlet air temperature
• Read and change cooling and cooling differential setpoints
• Read and change heating and heating differential setpoints
• Read and change the high and low temperature alarm settings
• Read and change the Gateway IP address, Device IP address, Subnet MASK, Trap IP address, and community string
• Read and change unit identication