nvent SpectraCool G280648G Series User manual

© 2022 nVent 89216438
Rev. A P/N 89216438
SpectraCool
Air Conditioner
G28 48 VdC Model
INSTRUCTION MANUAL

© 2022 nVent 89216438
- 2 -
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 nVent
Equipment Protection if further information is required.
WARRANTY AND RETURN POLICY
https://hoffman.nvent.com/en/hoffman/warranty-information
TABLE OF CONTENTS
Warranty and Return Policy............................................................................................................................................................. 2
HANDLING & TESTING THE AIR CONDITIONER........................................................................................................................... 3
HOW TO READ MODEL NUMBERS................................................................................................................................................. 3
INSTALLATION INSTRUCTIONS..................................................................................................................................................... 4
Dimensional Drawing ..................................................................................................................................................................................... 4
TECHNICAL INFORMATION............................................................................................................................................................ 6
Refrigerant Properties Chart (R134a) ........................................................................................................................................................... 6
Performance Data .......................................................................................................................................................................................... 7
6000 BTU/Hr. Unit Characteristics................................................................................................................................................................ 7
Wire Diagrams................................................................................................................................................................................................. 8
G280648GXXX Generic Wire Diagram (actual unit options may vary) .............................................................................................. 8
MAINTENANCE................................................................................................................................................................................ 9
Compressor..................................................................................................................................................................................................... 9
Inlet Air Filter ................................................................................................................................................................................................... 9
How To Remove, Clean or Install a New Inlet Air Filter ............................................................................................................................... 9
Condenser and Evaporator Air Movers......................................................................................................................................................... 9
Refrigerant Loss............................................................................................................................................................................................ 10
Service Data .................................................................................................................................................................................................. 10
G28 Series Components List....................................................................................................................................................................... 10
Electronic Controlling Section....................................................................................................................................................... 11
DIGITAL THERMOSTAT CONTROLLER (OPTIONAL)................................................................................................................................. 11
OVERVIEW..................................................................................................................................................................................................... 11
ENERGIZING THE CONTROLLER ................................................................................................................................................................ 11
Keypad........................................................................................................................................................................................................... 12
Main eld....................................................................................................................................................................................................... 12
Icons .............................................................................................................................................................................................................. 12
DISPLAYING AND CHANGING PROGRAM SETTINGS ...............................................................................................................14
Table 1: HEAT/COOL OPERATING PARAMETERS..................................................................................................................................... 14
Table 2: ALARM PARAMETERS................................................................................................................................................................... 14
REAL-TIME-CLOCK SETTING....................................................................................................................................................................... 15
VIEW ALARMS .............................................................................................................................................................................................. 15
VIEW THE ALARMS IN THE ALARM HISTORY FOLDER............................................................................................................................ 15
TO RESET THE ALARMS IN ALARM HISTORY FOLDER............................................................................................................................ 16
TO RESET PARAMETERS TO FACTORY DEFAULT...................................................................................................................................... 17
DISPLAYING TEMPERATURE DATA ON SCREEN ...................................................................................................................................... 17
COMPRESSOR RESTART TIME DELAY....................................................................................................................................................... 17
ALARM OUTPUT CONTACT......................................................................................................................................................................... 17
ALARM INPUT CONNECTION.......................................................................................................................................................18
PRIMARY-SECONDARY (PS) MODE............................................................................................................................................................ 18
Connecting units together in Primary/Secondary mode............................................................................................................19
LEAD-LAG (LL) MODE .................................................................................................................................................................................. 20
Connecting units together in Lead/Lag mode ........................................................................................................................................... 20
AIR CONDITIONER UNIT REMOTE COMMUNICATION FEATURES .......................................................................................................... 22
SOFTWARE AND CONFIGURATION FILE DOWNLOADS ........................................................................................................................... 22
USING HOFFMAN PC INTERFACE TOOL.....................................................................................................................................23
TROUBLE SHOOTING ....................................................................................................................................................................26
Basic Air Conditioning Trouble Shooting Check List................................................................................................................................. 26
Symptoms and Possible Causes: ............................................................................................................................................................... 27
F-GAS INFORMATION....................................................................................................................................................................27

© 2022 nVent
89216438 - 3 -
RECEIVING THE AIR CONDITIONER
Inspect the air conditioner and check for concealed damage that may have occurred during shipment. Damage
evident upon receipt should be noted on the freight bill. Save the packing material and request an inspection.
Then le a claim with the delivering carrier within 15 days of delivery.
nVent Equipment Protection cannot accept responsibility for freight damages; however, we will assist you in any
way possible.
HANDLING & 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.
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
TEST FOR FUNCTIONALITY BEFORE MOUNTING THE AIR CONDITIONER TO THE ENCLOSURE.
Refer to nameplate for proper electrical current requirements, and then connect power cord to a properly
grounded power supply. Minimum circuit ampacity should be at least 125% of the amperage shown in the
design data section for the appropriate model. 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 to ten minutes. You will need to set the cooling thermostat 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 on page 6 for specics on how the unit operates when powered up.
HOW TO READ MODEL NUMBERS
G28 06 48 G150
1234
1. Identies the type/family of air conditioner and the approximate height (i.e. G28 = Global family
about 28” high).
2. This is the air conditioner’s listed capacity in BTU/Hr. at rated conditions. (i.e. 06 = 6000 BTU/Hr.
at 131/131 F)
3. 48 = 48 Volts DC
4. Unique set of numbers for each air conditioner which identies the accessories on a model.

© 2022 nVent 89216438
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INSTALLATION INSTRUCTIONS
1. Inspect the air conditioner. Verify proper functionality before mounting the air conditioner, see
HANDLING & TESTING THE AIR CONDITIONER on page 3.
2. Using the mounting gasket kit provided with the unit, install gaskets to the air conditioner.
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. Allow unit to remain upright for a minimum of ve minutes before starting. Caution!
Air conditioner must be in upright position during operation.
5. 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.
6. Set thermostat for required cabinet temperature. Refer to on page 6 for thermostat
adjustment & operation.
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© 2022 nVent
89216438 - 5 -
28-1000-13
SURFACE MOUNT
Figure 1
Cutout Dimensions

© 2022 nVent 89216438
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TECHNICAL INFORMATION
REFRIGERANT PROPERTIES CHART (R134A)
°F °C Pressure °F °C Pressure
-40 -40 -14.7 60 15.6 58
-35 -37.2 -12.3 65 18.3 64
-30 -34.4 -9.7 70 21.1 71.5
-25 -31.7 -6.8 75 23.9 78
-20 -28.9 -4 80 26.7 86.7
-15 -26.1 085 29.4 95
-10 -23.3 290 32.2 105
-5 -20.6 495 35 113.3
0-17.8 7.5 100 37.8 125
5-15 9105 40.6 135
10 -12.2 12 110 43.3 146.7
15 -9.4 15 115 46.1 157.5
20 -6.7 18.5 120 48.9 170
25 -3.9 22 125 51.7 185
30 -1.1 26 130 54.4 197.5
35 1.7 30 135 57.2 213.3
40 4.4 35 140 60 230
45 7.2 40 145 62.8 246.7
50 10 45.5 150 65.6 263.8
55 12.8 51.5
N

© 2022 nVent
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PERFORMANCE DATA
6000 BTU/HR. UNIT CHARACTERISTICS
Model G280648GXXX
Dimensional Data
Height (in./mm) 28.60/726
Width (in./mm) 17.01/432
Depth (in./mm) 11.18/284
Unit Weight (lb./kg) 84/38
Unit Protection Rating Type 12/4/4X/3R
Cooling Data
Refrigerant R134A
Refrigerant Charge (oz/grams) 24/680
Cooling Capacity at 95 F enclosure 95 F ambient (BTU/Hr./W) 5250/1540
Cooling Capacity at Max Conditions (BTU/Hr./W) 6500/1900
Maximum Ambient Temp (°F/°C) 131/55
Minimum Ambient Temp (°F/°C) -40/-40
Enclosure Airow (CFM) 220
External Airow (CFM) Variable, 300 max
Condensate Management Hose discharge/Optional
powered C/E
Electrical Data
Rated Voltage (VDC) 48
Rated Frequency DC
Voltage Range 39-57
Cooling Amps at Max Conditions 17.7
Evaporator Fan RLA 0.8
Condenser Fan RLA 2.2

© 2022 nVent 89216438
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WIRE DIAGRAMS
G280648GXXX GENERIC WIRE DIAGRAM (ACTUAL UNIT OPTIONS MAY VARY)
ENG
BY
DATE
ECO/PDP
DESCRIPTION
REV.
DRAWING NO. SIZE
TITLE
NONE
SCALE
CHECKED
APPROVED
DATE
DO NOT SCALE DRAWING
SolidWorks Drawing
TOLERANCES:
ONE PLACE DECIMAL
.1
TWO PLACE DECIMAL
.03
THREE PLACE DECIMAL
.015
HOLE DIA
.005
ANGLES
2
PROJECTION
THIRD ANGLE
UNLESS OTHERWISE SPECIFIED
DIMENSIONS AND TOLERANCES IN INCH
FINISH
MATERIAL
PART NO.
THE INFORMATION CONTAINED IN THIS DRAWING IS THE
SOLE PROPERTY OF HOFFMAN ENCLOSURES INC.
ANY REPRODUCTION IN PART OR AS A WHOLE
WITHOUT THE WRITTEN PERMISSION OF
HOFFMAN ENCLOSURES INC. IS PROHIBITED.
PROPRIETARY AND CONFIDENTIAL
DRAWN
A
SHEET
5.00
4.25
89216429 REV.A
NOTES:
MATERIAL: SEE McLEAN SPEC #10-1370-00. 1.
89216429
3/1/2022
RS
NA
NA
SEE NOTES
89216429
---
---
A
3/1/2022
RS
CA-20231850
INITIAL RELEASE
MR
P2P G28 DC ACU10
W/HTR
1 OF 1

© 2022 nVent
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MAINTENANCE
COMPRESSOR
The compressor requires no maintenance. It is hermetically sealed, properly lubricated at the factory and should
provide years of satisfactory operating service.
Under no circumstances should the access tting covers be loosened, removed or tampered with.
Breaking of seals on compressor access ttings during warranty period will void warranty on hermetic system.
Recharging ports are provided for the ease and convenience of reputable refrigeration repair service personnel for
recharging the air conditioner.
INLET AIR FILTER
This air conditioner was designed with a dust resistant condenser coil. This allows it to be run lterless in most
applications. The air conditioner is shipped with a lter in place for your convenience. For lterless operation,
simply remove the lter. Should you decide the lter is necessary in your application, regular maintenance to
clean this lter will assure normal operation of the air conditioner. The easily removable inlet air lter is located
behind the front cover. If necessary lter maintenance is delayed or ignored, the maximum ambient temperatures
under which the unit is designed to operate will be decreased.
If the compressor’s operating temperature increases above designed conditions due to a dirty or clogged
lter (or plugged condenser coil), the air conditioner’s compressor will stop operating due to actuation of the
thermal overload cut-out switch located on the compressor housing. As soon as the compressor temperature
has dropped to within the switch’s cut-in setting, the compressor will restart automatically. However the above
condition will continue to take place until the lter or coil has been cleaned. It is recommended that power to
the air conditioner be interrupted intentionally when abnormally high compressor operating temperature causes
automatic shut-down of the unit. The above described shut-down is symptomatic of a clogged or dirty lter, thus
causing a reduction in cooling air ow across the surface of the compressor and condenser coil.
HOW TO REMOVE, CLEAN OR INSTALL A NEW INLET AIR FILTER
RP aluminum washable air lters are designed to provide excellent ltering eciency with a high dust holding
capacity and a minimum amount of resistance to air ow. Because they are constructed entirely of aluminum,
they are lightweight and easy to service. To achieve maximum performance from your air handling equipment, air
lters should be cleaned on a regular basis.
The inlet air lter is located behind the front cover. The lter may be accessed for cleaning or replacement
through the slots in the side panels.
Cleaning Instructions:
1. Clean the lter with warm water from the exhaust side to the intake side. DO NOT USE CAUSTICS.
2. After ushing, allow the lter to drain. Placing a lter corner down will assure complete drainage.
CONDENSER AND EVAPORATOR AIR MOVERS
Impeller motors require no maintenance. All bearings, shafts, etc. are lubricated during manufacturing for the life
of the motor.
If the condenser impeller motor (ambient impeller) should fail, it is not necessary to remove the air conditioner
from the cabinet or enclosure to replace the blower. The condenser blower is mounted on its own bulkhead and is
easily accessible by removing the front cover.
Caution! Operation of the air conditioner in areas containing airborne caustics or chemicals can rapidly
deteriorate lters, condenser coils, blowers and motors, etc. Contact nVent for special recommendations.

© 2022 nVent 89216438
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REFRIGERANT LOSS
Each air conditioner is thoroughly tested prior to leaving the factory to insure against refrigeration leaks. Shipping
damage or microscopic leaks not found with sensitive electronic refrigerant leak detection equipment during
manufacture may require repair or recharging of the system. This work should only be performed by qualied
professionals, generally available through a local, reputable air conditioning repair or service company.
Should the refrigerant charge be lost, access ports on the suction and discharge sides of the compressor are
provided for recharging and/or checking suction and discharge pressures.
Refer to the data on the nameplate which species the type of refrigerant and the charge size in ounces.
Before recharging, make sure there are no leaks and that the system has been properly evacuated into a
deepvacuum.
SERVICE DATA
G28 SERIES COMPONENTS LIST
Part Description G280648GXXX
Coil, Condenser 89051206
Coil, Evaporator 28-6010-00
Compressor 89174109
Compressor Controller 89174133
Controller 89202719
Filter, Air, Reusable 89119662
Filter/Dryer 52-6028-00
Heater, Compressor or Condenser Pan (optional) 10-1030-08
Thermistor 89075654
Impeller, Condenser 89102441
Impeller, Evaporator 89102440
Condenser Impeller Controller 89122338
Relay, Compressor 10-1005-22
Optional Communication Board 89145457
Fuse, Controller 89085114

© 2022 nVent
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ELECTRONIC CONTROLLING SECTION
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: Hoffman network card (RAC module) is optional accessory, therefore, some of the air
conditioners ship without the network card but it is upgradeable 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).
CONTROLLER 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 1: 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
ᵒC White When operating temperature in degrees Celsius ON
ᵒF 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
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

© 2022 nVent
89216438 - 13 -

© 2022 nVent 89216438
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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
TABLE 1: HEAT/COOL OPERATING PARAMETERS
Mnemonic Parameter Description Default Value Range
CSt (1) Cooling setpoint 80 F 72 F to 120 F
Cd (Cd1) (1) Cooling differential 7 F 2 F to 25 F
Cd2 (4) Cooling differential 2 15 F
HSt (2) (3) Heating setpoint 50 F 45 F to 60 F
Hd (3) Heating differential 7 F 2 F to 25F
NOTES: (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
TABLE 2: 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 configurable

© 2022 nVent
89216438 - 15 -
REAL-TIME-CLOCK SETTING
This controller is equipped with a real time clock for logging the time and date of alarm activities. There are ve
parameters designating to the minute, hour, year, month of the year, and day of the month as illustrated in below
table.
Mnemonic Par Description
t01 Unit of hour (0 - 23)
t02 Unit of minute
t03 Unit of year
t04 Unit of month
t05 Unit of day
SEt Save
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.

© 2022 nVent 89216438
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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
TO RESET THE ALARMS IN ALARM HISTORY FOLDER
The controller is designed with ability to reset or clear the alarm history
1. Follow instructions above to enter the passcode and open the reset folder (rStF).
2. The screen displays rSAL on line 2 and nO on line 1, press button the nO is ashing
3. 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
4. Press arrow to navigate to ESC, then press to returns to rStF screen.
5. 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.

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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 0to 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 button 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)

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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.
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 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 equiped 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

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CONNECTING UNITS TOGETHER IN PRIMARY/SECONDARY MODE
Primary
Device ID 1 Secondary Device ID 2 Secondary Device ID 3 Secondary Device ID 10
Figure 2: Primary-secondary network connectivity
To congure 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 0to 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)
LL (lead-lag)
PS (primary-secondary) SA
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

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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.
LEAD-LAG (LL) MODE
Lead-lag (LL) 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. LL mode is congured
manually in the eld after the installation. This option allows the user to operate two air conditioners in a staged
cooling conguration. The controller will alternate which air conditioner is the rst stage. To support LL mode,
four parameters, H01, H02, H03, and H14 need to be congured. H01 species the operating mode, H02 species
the device ID, H03 species the total number of the units in the group network, and H14 is the LL strategy
selection.
The two controllers is communicated through eldbus interface as illustrated in Figure 3. In the lead-lag mode
the controller supports
• Lead-lag staged cooling uses two cooling differential temperature settings Cd1 and Cd2. The lead air conditioner
will begin cooling at SP+Cd1 and the lag air conditioner will begin cooling at SP+Cd1+Cd2. Cooling will stop when
the temperature drops to SP.
• The two air conditioners will take turns being the lead and lag. Alternating can be done in time based or every
cooling cycle and is congured with H14.
CONNECTING UNITS TOGETHER IN LEAD/LAG MODE
Lead - Device ID 1 Lag - Device ID 2
Figure 3: Lead-Lag network connectivity