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 flow.
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 flow.
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 flow.
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 flow.
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 flow.
Check refrigerant charge
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