AHT Cooling Systems GmbH
24-hour defrosting block:
If "---" is shown briefly on the display and then the
temperature, the 24 hour defrosting block is active.
2.) End the semi-automatic defrosting:
The device automatically reverts to normal mode.
The current temperature is shown on the display
again.
Alarm display and acknowledgment
Alarm display:
The fault code flashes alternately on the display with
the temperature for several minutes. Thereafter, only
the point flashes (see → Fig. 2.1 No. 5).
With each full hour, the fault code is shown on the
display for approx. 10 minutes.
Calling up the fault code in-between:
Press the [STANDBY] button briefly.
Depending on the fault, an acoustic signal can also
be issued by a built-in buzzer.
Alarm acknowledgment:
The fault code or the flashing point and the
acoustic signal CANNOT be acknowledged.
List of fault codes:
Fault code
Bus
Col
F1
F2
F3
dFr/F3 alternating
Clock
EE
Flashing
temperature value
FU1**)
FU2**)
FU3**)
FU4**)
FU5**)
FU6**)
FU7**)
** only with speed-controlled compressor (VS)
AHT electronic controller (SECOP)
There are 3 buttons available as operating elements,
which are allocated as follows:
on18.05.2018 11:08
Meaning
Bus fault
Address collision bus
Sensor fault F1
Sensor fault F2
Sensor fault F3
Defrosting system fault
Time/date fault
Data backup fault
Excessive temperature alarm
Communication fault
controller/inverter
Overvoltage fan output of the
inverter
Compressor start fault
Compressor overvoltage
Inverter excessive
temperature
Inverter internal fault
Inverter supply voltage outside
the limits
361929_0917_BA_SM_V4_06.09.2017_U_enUS_DRUCK.docx
4
Fig. 3: Electronic controller, operating elements and screen
displays
No.
Operating element
Function
Application change (A1-A4)
1
Button [+/-]
Increase bus address
Button [MAN.
Start semi-automatic
2
DEFROST]
defrosting
Start defrosting manually
Button
Switch the cooling function
[STANDBY
on or off
3
RESET]
Call up fault code (if point
flashes)
Acknowledge acoustic alarm
No.
Display
Illuminated red point
4
(next to the horn signal)
Switch the cooling function on and off
Switch cooling function off (start the defrosting manually):
Press the [STANDBY RESET] button for
minimum 3 sec. "---" is shown on the display.
Switch on the cooling function:
Press the [STANDBY RESET] button for
minimum 3 sec. The current temperature
appears on the display screen.
Setting the application
The following applications A1-A4 (customer-specific
approval) can be selected.
Display application set:
Press the [+/-] button briefly.
The currently set application is shown on the
display, e.g. "A1".
If no changes are required, the display returns to the
temperature display after approx. 5 seconds.
Change application:
By pressing the [+/-] button several times,
you can run through all the released
applications.
Accept new entry:
The newly set application is accepted
automatically approx. 5 seconds after
pressing the button for the last time.
Assigning the bus address
Before assigning, the devices must be networked
with a corresponding bus cable. On the last device,
the bus cabling must be terminated with a terminal
Meaning
Alarm display
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