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F.747 Internal error in programming unit
F.747
System characteristics
Heat pump cannot be operated via HMI programming
unit.
Cause
Internal HMI programming unit fault
Measures
Replace HMI programming unit.
F.748 Fault in touch panel of programming unit
F.748
System characteristics
HMI programming unit has limited or no functionality
Cause
Internal HMI programming unit fault
Measures
Replace HMI programming unit.
F.749 Firmware versions of the control units are incompatible with each other
F.749
System characteristics
Heat pump not working
Cause
Software versions of the electronics modules and
refrigerant controller are not compatible.
Measures
Check the software versions of the electronics mod-
ules and refrigerant circuit controller via ViGuide. Run
software update if required.
F.764 Another CAN bus subscriber reports a fault
F.764
System characteristics
■
Heat pump cascade:
Heating/cooling capacity and/or DHW output
impaired
■
System network:
Behaviour of the heat pump in the system network
depending on other pending messages
Cause
Fault message from another CAN bus subscriber (e.g.
slave heat pump or other Viessmann appliance)
Measures
Check for fault on CAN bus subscribers.
Messages
Fault messages (cont.)
6218234
Diagnosis
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