Daikin UATYQ25ABAY1 User manual

Operation manual
Rooftop Packaged Unit
Models:
UATYQ20ABAY1
UATYQ25ABAY1
UATYQ30ABAY1
UATYQ45ABAY1
UATYQ50ABAY1
UATYQ55ABAY1
UATYQ65ABAY1
UATYQ75ABAY1
UATYQ90ABAY1
UATYQ110ABAY1
UATYQ115ABAY1
UATYQ20AFC2Y1
UATYQ25AFC2Y1
UATYQ30AFC2Y1
UATYQ45AFC2Y1
UATYQ50AFC2Y1
UATYQ55AFC2Y1
UATYQ65AFC2Y1
UATYQ75AFC2Y1
UATYQ90AFC2Y1
UATYQ110AFC2Y1
UATYQ115AFC2Y1
UATYQ20AFC3Y1
UATYQ25AFC3Y1
UATYQ30AFC3Y1
UATYQ45AFC3Y1
UATYQ50AFC3Y1
UATYQ55AFC3Y1
UATYQ65AFC3Y1
UATYQ75AFC3Y1
UATYQ90AFC3Y1
UATYQ110AFC3Y1
UATYQ115AFC3Y1
Operation manual
Rooftop Packaged Unit English

Original instructions
Installation manual
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UATYQ*Y1
Packaged Rooftop
4P522681-1A
Contents
1 User Interface 4
2 Operating guide 5
2.1 Software menu 5
2.2 Main mask and menu 6
2.3 Switching ON/OFF he unit from keyboard 7
2.4 Temperatureandairowsetpointadjust 7
2.5 Clock menu and time slots setting 8
2.5.1 Time slots programming examples 9
2.6 Stop washing function (forced freecooling at unit start-up) 10
2.7 Summer/winter changeover from keyboard 11
2.8 Input/output visualization 12
2.9 Change language and unit and software data visualization 14
2.10 Alarms 15

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This operation manual is dedicated to the end user of the unit and it contains a brief description of all free access
functions of the unit control.
1 USER INTERFACE
The user interface is a LCD display with 4 rows, 20 columns and automatic backlight; the display has 6 function keys,
that are used to navigate the software menu and to set the parameters.
The key functions are described in the following.
This key, called “up arrow” , allows to scroll up the masks and to modify the value of each mask
eld,increasingit.
This key, called “down arrow” , allows to scroll up the masks and to modify the value of each
maskeld,decreasingit.
This key, called “Enter” ,conrmstheselectiondonetoaccessthemenubranchesandstoresa
parameterthathasbeenmodied.
This key, called “alarm”, allows to display active alarms and, in case, to reset them.
This key, called "prg" , allows to enter the software menu.
This key, called "esc" , allows to exit the displayed mask and to go back to the previous menu
level.

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2 OPERATING GUIDE
The operating guide describes the main control functions.
2.1 Software menu
Thesoftwareisorganizedwithamenuthatallowstoaccesstodi󰀨erentbranches,eachonecontainingoneormore
masksorscreens,withdi󰀨erentaccesslevels:free,partiallypassword-protectedorcompletelypassword-protected.
Pressing the keyfromanymask,thefollowingmenuloopisdisplayed:
With arrow keys it is possible to scroll the menu; the selected one is highlighted and marked by an arrow
ontheleft:
To enter the selected menu, press the "enter" key .
Thisisthemaskstreewithallsub-menus:
• The ones reported in underlined letters are free access menu;
• the ones reported in "italic letters" are partially password-protected menu;
• the ones reported in bold letters are completely password-protected menu.
The access to the password-protected menu is reserved to Service technicians.

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2.2 Main mask and menu
Whentheunitispowered,themainmaskisdisplayedontheunitdisplay,showinginitsrstrowtheindoortemperature
setpoint on the left and the local address of the unit on the right, in bigger fonts the read indoor temperature and on
the last row the unit status on the left and the current time on the right.
todisplaytheunitworkingmode,thetimeslotsactivation,thedehumidicationactivation(notavailable),the
setpoint compensation activation (where enabled).
to display if the unit is in defrost, in freecooling or in freeheating mode.
to display the unit active compressors.
to display if high pressure alarm prevention function in summer mode is active, if the supply temperature limit
is active and if the antifreeze function is enabled and active.
to display the delivery and return (if present) air fans working mode (manual or automatic).
to display if the condensate tray electrical heater is active.
to display if the washing function (forced freecooling at unit start-up) is active.

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to display if the low pressure alarm prevention function in winter mode is active for circuits 1 and 2.
2.3 Switching ON/OFF he unit from keyboard
select "On/OFF unit" menu "Enter" "Enter"to switch ON/OFF the unit.
If time slots are active, the unit will start running only if it is programmed to be ON in that time slot.
IftheunitON/OFFswitchingfromasupervisorsystemisenabled,theserialconsentisnecessaryforthee󰀨ective
unit starting-up.
IftheunitON/OFFswitchingfromdigitalinputisenabled,theON/OFFdigitalinputmustbeclosedforthee󰀨ective
unit starting-up.
If even only one of the previous starting-up systems does not give its consent, the unit will not start running.
2.4 Temperatureandairowsetpointadjust
select "Setpoint" menu "Enter" .
FromS0mask,theindoortemperaturesetpointinsummermode(cooling)canbeadjusted:press"enter"key ,
adjustthesetpointvaluewitharrowkeysandpress againtoconrmthenewvalue.
Iftimeslotsareactive,thesetpointcannotbemodiedfromthismask,butonlyfromthespecicmaskoftheClock
menu.
fromS1mask,theindoortemperaturesetpointinwintermode(heating)canbeadjusted:pressthekey ,
adjustthesetpointvaluewitharrowkeysandpress againtoconrmthenewvalue.
Iftimeslotsareactive,thesetpointcannotbemodiedfromthismask,butonlyfromthespecicmaskoftheClock
menu.
fromS5mask,thedeliveryairowcanbeadjusted:pressthekey ,adjustthesetpointvaluewitharrow
keys and press againtoconrmthenewvalue.
TherealairowcanbereadfromnextmaskS6.

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fromS7mask,displayedonlyforunitwithreturnfans,thereturnairowcanbeadjusted:press key,adjust
the setpoint value with arrow keys and press againtoconrmthenewvalue.
TherealairowcanbereadfromnextmaskS8.
2.5 Clock menu and time slots setting
select "Clock" menu .
Current time and date can be set from this mask, while the day is automatically updated.
to enable and set time slots, input the Clock menu password and press the key ; the factory Clock menu
password is 0001.
fromthismask,thedailytimeslotscanbeenabled(secondline)andswitcho󰀨theunitoutsidethetimeslots
(fourth line).
set start and end time of the daily time slot.
set the summer (cooling) indoor temperature setpoint inside the time slot (internal set, third line) and outside
the time slot (external set, fourth line).
set the winter (heating) indoor temperature setpoint inside the time slot (internal set, third line) and outside the
time slot (external set, fourth line).

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enable the weekly programming, if required.
set week days when the unit has to be in ON status (Y) or in OFF status (N).
2.5.1 Time slots programming examples
To better explain the time slots programming, two examples are reported in the following.
Example n. 1
Theunithastooperateeveryday:
• from07:00to20:00withsummersetpoint26.0°Candwintersetpoint21.0°C;
• from20:00to07:00withsummersetpoint30.0°Candwintersetpoint15.0°C.
Moreover, unit main fans must be always active.
MasksK2toK6havetobesetasfollows:
It is not required to set working days on mask K7, because weekly programming is disabled from mask K6.

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Example n. 2
TheunithastooperatefromMondaytoFriday,from07:30to19:30,withsummersetpoint24.0°Candwintersetpoint
20.5°C;moreover,unitfansmustbeswitchedOFFfrom19:30to07:30andtheunithastobecompletelyswitched
OFF on Saturday and Sunday.
MasksK2toK7havetobesetasfollows:
In case the “Unit OFF by time slot” function is enabled in mask K2, the external set in mask K4 can be
whatever value, because it is not considered by the unit thermoregulation due to the fact that unit is
switched OFF.
2.6 Stopwashingfunction(forcedfreecoolingatunitstart-up)
Unit with freecooling dampers and washing function enabled.
Main mask press "Enter" to stop washing function.

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2.7 Summer/winter changeover from keyboard
The unit must be switched OFF and the summer/winter changeover from keyboard must be enabled.
Select “Summer/Winter” menu "Enter"
"Enter" to change unit working mode.
If the changeover from digital input is enabled, mask R0 is not visualized.
If the automatic changeover is enabled, the changeover from winter mode to summer mode is done automatically
when the indoor air temperature rises above the summer setpoint, while the changeover from summer mode to winter
mode is done automatically when the indoor air temperature falls below the winter setpoint. In any case, the automatic
changeoverisdonewiththeunitinONstatus,sothecontrolwillrststopallactivedevices(compressors,electrical
heaters, etc.), except main fans, and it will restart them automatically when the changeover is done, following the
thermal load request.
In order to have the automatic summer/winter changeover working properly, winter setpoint must be
lower than summer setpoint; if not, the control will activate an alarm that will stop the unit; this alarm
will be automatically reset when the summer and winter setpoint are properly set.

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2.8 Input/output visualization
select "Input/Output" menu .
The mask displays intake air temperatures internal and external.
the mask displays the supply air temperature.
the mask displays circuit 1 and 2 refrigerant pressures.
The mask displays the CO2or VOC concentration, read by the air quality probe, if present.
themasksdisplaythedigitalinputstatuses:C=closed,O=open.
the mask displays the compressor statuses.
the mask displays the statuses of the external fans and of the 4-way reversing valves of circuit 1 and 2.

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the mask displays the main fan status.
the mask displays the electrical heater statuses, if present.
the mask displays the opening percentages of the external air damper and of the hot water valve, if present.
the mask displays the running percentage of external fans of circuit 1 and 2.
the mask displays the running percentage of delivery and return fans (if present).
themaskdisplaystheairpressuresreadfromtheairpressuretransducerofsupplyandreturnairow;please
note that this pressure is measured on fan nozzle and is not related in any way to the available static pressure.
the masks display the evaporation temperature, the defrost calculated setpoint and the defrost starting
countdown of circuits 1 and 2.

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the mask displays the NO11 auxiliary output status and the condensate tray electrical heater status.
2.9 Change language and unit and software data visualization
“Maintenance” menu "Enter"
From this mask the control language can be changed, choosing from those available. Press "Enter" change the
language.
themaskdisplaysthefollowingunitdata:serialnumber,factorytestingdateandfactorytesteridentication
code.
the mask displays the software code, version and release date and the unit model.
the mask displays the control board bios and boot versions and release dates.
the mask displays the control board model and type.
the mask displays the unit working hours.
the mask displays the working hours of compressors 1 and 2.

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the mask displays the working hours of compressors 3 and 4.
2.10 Alarms
When an alarm is triggered, the red "Alarm" key is on and the alarm digital output is activated.
By pressing the "Alarm" key, the last alarm is displayed; the other active alarms can be scrolled with arrow keys.
Thisisanexampleofanalarmmask:
Eachalarmisidentiedbyacode“ALxx”andthealarmcauseisdescribedinthemask.Toresetanactivealarm,
press and hold for at least 2 seconds the "Alarm" key; if the alarm has been successfully reset, the alarm mask
disappears and, if no other alarms are active, the red "Alarm" key is switched OFF. An alarm can be reset only if the
condition that has activated the alarm is not present anymore.
The manual reset of an alarm must be done only after checking the alarm cause and solving the
problem that has activated the alarm.
The improper reset of an alarm can cause serious damages to the unit or to its components.
On alarm history menu, last 150 alarms are stored. When the memory is full and another alarm is activated, the oldest
alarm is overwritten.
In the following, the full alarm list is reported with the main possible causes, some troubleshooting hints, the reset
mode, the action on the unit and on its components.
Thealarmresetmodeisreportedonthe“RESET”column:
• A=automatic:whenthealarmconditiondisappears,thealarmisautomaticallyreset;
• AC=automaticcontrolled:thealarmisautomaticallyresetforalimitednumberofattemptsinacertaintime,after
that the reset becomes manual;
• M=manualresetfromdisplayorfromsupervisor:thealarmmustbemanuallyresetbydisplayasdescribed
above or by the supervisor reset variable; for each alarm with manual reset, the reset day and time are stored on
the alarm history.
Inthe“OFFUNIT”column,itisreportedifthealarmstopsthewholeunitornot:
• Yes=thealarmstopstheunit;
• No=thealarmdoesnotstoptheunit,butonlytheconcerneddevices
CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL01 Overload
Compressor 1
Intervention of the thermal
protection compressor 1
Check working conditions.
M No Compressor 1
Check cabling, terminals and circuit
breaker of the motor.
Check adsorbed current.
Check compressor discharge
temperature.
AL02 Overload
Compressor 2
Intervention of the thermal
protection compressor 2
Check working conditions.
M No Compressor 2
Check cabling, terminals and circuit
breaker of the motor.
Check adsorbed current.
Check compressor discharge
temperature.

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CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL03 High pressure
Circuit 1
High pressure alarm from
circuit 1 (high pressure
switch)
Check condensing pressure.
M No All compressors
circuit 1
Check refrigerant charge.
Check condensing fan/s operation
Check the presence of warm
condensing air recycling.
Check condensing coil cleaning and
eventually clean it.
Reset the high pressure switch before
resetting the alarm in the controller.
Check the correct intervention set for
the high-pressure switch.
AL04 High pressure
Circuit 2
High pressure alarm from
circuit 2 (high pressure
switch)
Check working conditions.
M No All compressors
circuit 2
Check condensing pressure.
Check refrigerant charge.
Check condensing fan/s operation
Check the presence of warm
condensing air recycling.
Check condensing coil cleaning and
eventually clean it.
Reset the high pressure switch before
resetting the alarm in the controller.
Check the correct intervention set for
the high-pressure switch.
AL05 Antifreeze alarm Digital input 1 open Check working conditions. A (2) No Compressors (only
cooling mode)
AL06
High temp
threshold
exceeded
Indoor temperature exceeds
the max value set Check working conditions. A No None
AL07
Low temp
threshold
exceeded
Indoor temperature is lower
than the min value set Check working conditions. A (2) No None
AL08 Low pressure
Circuit 1 in summer
Low pressure alarm circuit 1
from the low-pressure switch
(cooling mode)
Check working conditions.
M No All compressors
circuit 1
Check evaporation pressure.
Check refrigerant charge
Check evaporation fans.
Check the correct intervention of the
low-pressure switch.
AL09 Low pressure
Circuit 2 in summer
Low pressure alarm circuit 2
from the low pressure switch
(cooling mode)
Check working conditions.
M No All compressors
circuit 2
Check evaporation pressure.
Check refrigerant charge
Check evaporation fans.
Check the correct intervention of the
low-pressure switch.
AL10 Low pressure
Circuit 1 in winter
Low pressure alarm circuit 1
from the low pressure switch
(heating mode)
Check working conditions.
M No All compressors
circuit 1
Check evaporation pressure.
Check refrigerant charge
Check evaporation fans.
Check the correct intervention of the
low-pressure switch.
AL11 Low pressure
Circuit 2 in winter
Low pressure alarm circuit 2
from the low-pressure switch
(heating mode)
Check working conditions.
M No All compressors
circuit 2
Check evaporation pressure.
Check refrigerant charge
Check evaporation fans.
Check the correct intervention of the
low-pressure switch.
AL12 Compressor 1
maintenance
It has been exceeded
Compressor 1 operating
hours threshold.
Check the compressor working
conditions. M (1) No None

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CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL13 Compressor 2
maintenance
It has been exceeded
Compressor 2 operating
hours threshold.
Check the compressor working
conditions. M (1) No None
AL14 Unit Maintenance It has been exceeded unit
operating hours threshold.
Unit check up. Perform the ordinary
maintenance operations. M (1) No None
AL15 Main fan overload/
interblock
Thermal protection ventilation
fan
Check working conditions.
MYes All
Check fans motor cabling, terminals and
adsorbed current.
Check thermal overload switch.
AL16 Filter dirty
The pressure drop across
theltermeasuredbythe
di󰀨erentialpressureswitchis
higher than the set value
Cleanorreplacetheairlters. M
No None
Calibrationofthedi󰀨erentialpressure
switchforcloggedlters. M
AL17 Not used - - - - -
AL18 Flow-switch alarm
Thedi󰀨erentialairpressure
switch detects a pressure
(airow)lowerthantheset
point
Checkworkingconditions(airowand
pressure).
MYes All
Check working operation of the
ventilation fans.
Check air distribution system.
Check the correct intervention of the
airowswitch.
AL19 Clock broken or
not present The clock board is defective Reboot the controller; if alarm persists, replace the main board. M No
None, hourly
programming not
operating
AL20 Summer setpoint
< winter setpoint
Summer set point is lower
than winter set point or
winter set point is higher
than summer set point and
automatic changeover is
enabled
Check for the correct temperature set
point (cooling and heating modes). AYes All
AL21 B1 probe broken or
disconnected
The reading of the probe B1
(supplyairowdi󰀨erential
pressure probe) exceeds the
operative range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL22 B2 probe broken or
disconnected
The reading of the probe B2
(returnairowdi󰀨erential
pressure probe) exceeds the
operative range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL23 B6 probe broken or
disconnected
The reading of the probe B6
(condensing pressure circuit
2) exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.

Original instructions
Installation manual
18
We reserve the right to make changes without any prior notice.
UATYQ*Y1
Packaged Rooftop
4P522681-1A
CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL24 B7 probe broken or
disconnected
The reading of the probe B7
(indoor air humidity) exceeds
the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL25 B4 probe broken or
disconnected
The reading of the probe
B4 (supply air temperature)
exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL26 B3 probe broken or
disconnected
The reading of the probe B3
(condensing pressure circuit
1) exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL27 B8 probe broken or
disconnected
The reading of the probe B8
(Outdoor air temperature)
exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL28 B5 probe broken or
disconnected
The reading of the probe
B5 (return air temperature)
exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL29 Heater 1 overload The circuti breaker of the
heater group 1 trips
Checkworkingconditions(airowand
temperature).
M No Heater group 1Check cabling and terminals of the
heaters and adsorbed current.
Check thermal switch.
AL30 Heater 2 overload The circuit breaker of the
heater group 2 trips
Checkworkingconditions(airowand
temperature).
M No Heater group 2Check cabling and terminals of the
heaters and adsorbed current.
Check thermal switch.
AL31
Generic serious
alarm by DIN .
Systemo󰀨
The serious alarm digital
input (DIN) is open Check external control. M Yes All
AL32
Generic alarm by
dig. input System
still on
The generic alarm digital
input is open Check extarnal control. M No None

Original instructions
Installation manual
19
We reserve the right to make changes without any prior notice.
UATYQ*Y1
Packaged Rooftop
4P522681-1A
CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL33 Compressor 3
Overload
Intervention of the thermal
protection compressor 3
Check working conditions.
M No Compressor 3
Check cabling, terminals and circuit
breaker of the motor.
Check adsorbed current.
Check compressor discharge
temperature.
AL34 Compressor 4
Overload
Intervention of the thermal
protection compressor 4
Check working conditions.
M No Compressor 4
Check cabling, terminals and circuit
breaker of the motor.
Check adsorbed current.
Check compressor discharge
temperature.
AL35 Compressor 3
maintenance
It has been exceeded
compressor 3 operating hours
threshold.
Check the working conditions of the
compressor. M (1) No None
AL36 Compressor 4
maintenance
It has been exceeded
compressor 4 operating hours
threshold.
Check the working conditions of the
compressor. M (1) No None
AL37-
65 Not used - - - - -
AL66 WARNING Circuit
1 in Prevent
Condensing pressure circuit
1 is higher than prevention
value (cooling mode)
Evaporation pressure circuit 1
is lower than prevention value
(heating mode)
Check working conditions.
A (2) No One compressor of
circuit 1
Check condensing pressure.
Check condensing fans and coil.
Checkcondensingcoilairow.
Check refrigerant charge
AL67 WARNING Circuit
2 in Prevent
Condensing pressure circuit
2 is higher than prevention
value (cooling mode)
Evaporation pressure circuit 2
is lower than prevention value
(heating mode)
Check working conditions.
A (2) No One compressor of
circuit 2
Check condensing pressure.
Check condensing fans and coil.
Checkcondensingcoilairow.
Check refrigerant charge
AL68 Di󰀨erentialprobe
supply
The value measured from
thesupplynairdi󰀨erential
pressure probe for the return
is outside the allowed range.
Checkairow.
A (2) No None
Checkairowdistributionsystem.
Checksupplydi󰀨erentialpressure
switch and its own connection hoses.
AL69 Di󰀨erentialprobe
return
The value measured from the
returnairdi󰀨erentialpressure
probe for the return is outside
the allowed range.
Checkairow.
A (2) No None
Checkairowdistributionsystem.
Checksupplydi󰀨erentialpressure
switch and its own connection hoses.
AL70 B9 probe broken or
disconnected
The reading of the probe
B9 (indoor air CO2 or VOC)
exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.
AL71 B10 probe broken
or disconnected
The reading of the probe B10
(outdoor air relative humidity)
exceeds the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board.

Original instructions
Installation manual
20
We reserve the right to make changes without any prior notice.
UATYQ*Y1
Packaged Rooftop
4P522681-1A
CODE DESCRIPTION MAIN CAUSES CHECKS AND TROUBLESHOOTING RESET UNIT
OFF ITEMS OFF
AL72 Board 2 Lan
disconnected
Interrupted communication
between main and expansion
boards
Check for correct power supply to the
expansion board.
M No
All components
and fuctions
directly related
to the expansion
board
Check for the connection between main
and expansion boards.
Communication setup.
AL73
B1 slave
probe broke or
disconnected
The reading of the probe B1
of expansion board exceeds
the range
Check working conditions.
M No
All components
and fuctions
directly related to
the probe
Check in the controller for the correct
probe reading range .
Check the correct reading of the probe
and eventually replace it.
Check probe wiring and terminals.
Check correct functioning of the
analogic input of the main board
AL74
Circuit 1 High
pressure from
transd.in cooling
Tent.:x/y
High pressure alarm of
cooling circuit 1 in cooling
(summer) mode from
pressure transducer.The
attempt “x” of the maximum
number “y” of attempts
is displayed; when the
maximum number of attempts
is reached, the alarm reset
becomes manual.
Check working conditions.
AC No All compressors of
circuit 1
Check condensing pressure.
Check condensing fans and coil.
Checkcondensingcoilairow.
Check refrigerant charge.
Check pressure probe.
AL75
Circuit 2 High
pressure from
transd.in cooling
Tent.:x/y
High pressure alarm of
cooling circuit 2 in cooling
(summer) mode from
pressure transducer.The
attempt “x” of the maximum
number “y” of attempts
is displayed; when the
maximum number of attempts
is reached, the alarm reset
becomes manual.
Check working conditions.
AC No All compressors of
circuit 2
Check condensing pressure.
Check condensing fans and coil.
Checkcondensingcoilairow.
Check refrigerant charge.
Check pressure probe.
AL76
Circuit 1 Low
pressure from
transd.in heating
Tent.:x/y
Low pressure alarm of
cooling circuit 1 in heating
(winter) mode from pressure
transducer. The attempt “x”
of the maximum number
“y” of attempts is displayed;
when the maximum number
of attempts is reached,
the alarm reset becomes
manual."
Check working conditions.
AC No All compressors of
circuit 1
Check evaporating pressure.
Check evaporating fans and coil.
Checkevaporatingcoilairow.
Check refrigerant charge.
Check pressure probe.
AL77
Circuit 2 Low
pressure from
transd.in heating
Tent.:x/y
Low pressure alarm of
cooling circuit 2 in heating
(winter) mode from pressure
transducer. The attempt “x”
of the maximum number
“y” of attempts is displayed;
when the maximum number
of attempts is reached,
the alarm reset becomes
manual."
Check working conditions.
AC No All compressors of
circuit 2
Check evaporating pressure.
Check evaporating fans and coil.
Checkevaporatingcoilairow.
Check refrigerant charge.
Check pressure probe.
AL78
WARNING Circuit
1 in low pressure
prevention
Evaporation pressure of
circuit 1 in heating (winter)
mode is lower than the low
pressure prevention value
Check working conditions.
A (2) No A compressor of
circuit 1
Check evaporating pressure.
Check evaporating fans and coil.
Checkevaporatingcoilairow.
Check refrigerant charge