Viessmann VITOCAL 300-A Installation And Service Instructions Manual page 124

Troubleshooting
Control unit diagnostics
Message
UBE HC3 R/C KM BUS
¸C5 Power-OFF
UC9 Refrigerant circuit
UCA Primary source
¸CB Primary temp.
UCC Coding card
UCD KM BUS Vitocom
UCE KM BUS ext. CE
UD1 Compressor
124
(cont.)
Cause
Communication error
KM BUS remote control;
heating circuit with mixer
M3
Power-OFF (triggered
by the power supply uti-
lity)
Safety high pressure
switch has responded
Primary circuit monitor-
ing has responded
Min. primary inlet tem-
perature not achieved
The coding card cannot
be read
Communication error
KM BUS Vitocom 100
Communication error
KM BUS external
extension H1
Thermal compressor
relay or safety element
of the full wave soft star-
ter (if fitted) has re-
sponded
Measures
Check remote control con-
nections and coding (see
page 53); switch ON re-
mote control
No measures required
&
Check the flow and
return temperature sen-
sors
&
Check primary and sec-
ondary circuits for pres-
sure and throughput (see
also error UA9)
&
Have heat pump tested
by a refrigeration engi-
neer
Note
Switch appliance ON and
OFF after removing fault.
Check whether jumper
3X3.9 is inserted after
3X3.8
Check the evaporator for
throughput
Check the coding card and
replace if required
Check the Vitocom 100
connections and connect-
ing cables
Check external
extension H1 connections
and connecting cables
Reset the thermal relay,
check the setting, set de-
livered condition ("Reset",
see operating instruc-
tions), check the connec-
tion, check the coil
resistance