Viessmann Vitoligno 300-P Service Instructions For Contractors page 81

Fault display
(cont.)
Fault code System characteris-
on the dis- tics
play
9C Solar circuit pump
switched OFF; no cyl-
inder heating through
the solar thermal sys-
tem.
Collector frost protec-
tion function starts, if
enabled and if
required
9F Control mode
A7 Control mode as per
delivered condition
AA Control mode
B1 Control mode
B4 Regulates as if the
outside temperature
were 0 °C
B5 Control mode
B6 Burner blocked
B7 Burner blocked
B9 Burner blocked
BA Mixer M1 continues
to regulate
Cause
Break, cylinder
temperature sen-
sor
External Vitosolic
solar control unit:
Connection to S2
Solar control unit
fault; displayed if a
fault without fault
code occurs at the
solar control unit
Faulty program-
ming unit
Configuration fault
Communication
error, program-
ming unit
Internal electronics
fault
Internal electronics
fault
Incorrect boiler
coding card
Boiler coding card
missing or faulty
Incorrect transmis-
sion of the boiler
coding card details
Communication
error, extension kit
for heating circuit
with mixer M1
Troubleshooting
Measures
Check the cylinder tem-
perature sensor (see
page 85)
Check solar control unit
Separate installa-
tion and service
instructions
Replace programming
unit
Check coding configura-
tion
Check connections and
replace the programming
unit, if required
Replacing the control unit
Replacing the control unit
Insert the correct boiler
coding card
Plug in boiler coding card
or replace, if faulty
Replace boiler coding
card, possibly replace the
PCBs in the control unit
Check extension kit con-
nections and code. Start
the extension kit
81