Viessmann Vitocal 300-G Installation And Service Instructions Manual page 128

Troubleshooting
Control unit diagnostics
ID Message
(priority)
BB KM BUS mixer
NC ("U")
BC KM BUS FB
HK1 ("U")
BD KM BUS FB
HK2 ("U")
BE KM BUS FB
HK3 ("U")
C2 Power supply
monitor ("U")
C5 Power-OFF
("i")
C9 Refrigerant
circuit ("U")
128
(cont.)
1. Cause
2. Measures
1. Communication error KM BUS mixer
NC, internal fault extension set for
one heating circuit with mixer
2. Check appliance connections and
coding
1. Communication error KM BUS
remote control; heating circuit 1
2. Check appliance connections and
coding; switch on appliance
1. Communication error KM BUS
remote control; heating circuit 2
2. Check appliance connections and
coding; switch on appliance
1. Communication error KM BUS
remote control; heating circuit 3
2. Check appliance connections and
coding; switch on appliance
1. Fault, power supply compressor,
power circuit; phase monitor faulty
2. Power supply, rotating field, asym-
metry, check for phase failure and
components
1. Power-OFF enabled
2. No measures required
1. Safety HP switch has responded
2. Check the flow and return tempera-
ture sensors, check the primary and
secondary circuits for pressure and
throughput; ask your local refrigera-
tion engineer to check the heat
pump, if required.
Note
Switch appliance off and on after
removing the cause for the message.
Access
right
Customer
Customer
Customer
Customer
Customer
Customer
Customer