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97
CODE
DESCRIPTION
MAIN CAUSE POTENTIAL
RESOLUTION OF THE PROBLEM
RESET
UNIT
OFF
DEVICES
SWITCHED
OFF
AL27
Probe U8
malfunctioning or
disconnected
The value measured by probe U8
(external air temperature) is outside the
operating range.
Check the operating conditions.
Check the probe setpoint range stored in
the controller.
Test the probe: if it does not work
correctly, replace it.
Check the electrical connection of the
probe.
Check the input of the controller board.
M No
All devices and
functions
whose setting
is connected to
the probe
AL28
Probe U5
malfunctioning or
disconnected
The value measured by probe U5 (air
temperature in return line) is outside the
operating range.
Check the operating conditions.
Check the probe setpoint range stored in
the controller.
Test the probe: if it does not work
correctly, replace it.
Check the electrical connection of the
probe.
Check the input of the controller board.
M No
All devices and
functions
whose setting
is connected to
the probe
AL29
Thermal overload
switch in heater 1
The thermal overload switch in the
heaters featured in bank 1 has tripped.
Check the operating conditions (air flow
rate and temperature).
Check the heater wiring and the power
absorption.
Check the thermal overload switch.
M No
Heaters in
bank 1
AL30
Thermal overload
switch in heater 2
The thermal overload switch in the
heaters featured in bank 2 has tripped.
Check the operating conditions (air flow
rate and temperature).
Check the heater wiring and the power
absorption.
Check the thermal overload switch.
M No
Heaters in
bank 2
AL31
A serious general
alarm has been
output by the digital
input. System OFF
The digital input associated to a serious
external alarm has been opened.
Check the cause leading to opening of the
digital input.
M Yes
All
AL32
A non serious
general alarm has
been output by the
“System ON” digital
input.
The digital input associated to a non
serious external alarm has been
opened.
Check the cause leading to opening of the
digital input.
M No
None
AL33
Thermal overload
switch in
compressor 3
The thermal overload switch in
compressor 3 has tripped.
Check the operating conditions.
Check the motor wiring and the power
absorption.
Check the electric motor fitted in the
compressor.
Check the discharge temperature.
Check the thermal overload switch.
M No
Compressor
3
AL34
Thermal overload
switch in
compressor 4
The thermal overload switch in
compressor 4 has tripped.
Check the operating conditions.
Check the motor wiring and the power
absorption.
Check the electric motor fitted in the
compressor.
Check the discharge temperature.
Check the thermal overload switch.
M No
Compressor
4
AL35
Compressor 3
maintenance
The threshold relating to the hours of
operation of compressor 3 has been
exceeded.
Check for compressor operation.
M (1)
No None
AL36
Compressor 4
maintenance
The threshold relating to the hours of
operation of compressor 4 has been
exceeded.
Check for compressor operation.
M (1)
No None
AL37-
AL65
Not used
AL66
WARNING
Circuit 1 in Prevent
The condensing pressure in circuit 1 -
summer mode - is higher than the
Prevent value.
Check the operating conditions.
Check the refrigerant level.
A (3)
No
One
compressor in
circuit 1
AL67
Warning
Circuit 2 in Prevent
The condensing pressure in circuit 2 -
summer mode - is higher than the
Prevent value.
Check the operating conditions.
Check the refrigerant level.
A (3)
No
One
compressor in
circuit 2
AL68
Differential probe in
delivery line
The differential air pressure probe in the
delivery line has detected a value
outside the min. and max. setpoints
stored in controller screen Y6.
Check the air flow rate in the delivery line.
Check the air distribution system.
Check for correct operation of the
differential air pressure probe and correct
positioning of the pipes for pressure
measurement.
A (3)
No None