Viessmann VITOTRONIC 200 Service Instructions Manual page 54

Troubleshooting
Messages
(cont.)
Message
Code/system characteris-
tics
B1 KM BUS refrig. circ. 1
■ Refrigerant circuit ena-
bled; limited compres-
sor operation. If this
operation is not possi-
ble, the compressor
shuts down after a few
minutes.
■ Energy statement (see
page 91) will not be
calculated correctly.
B2 KM BUS refrig. circ. 2
■ Refrigerant circuit ena-
bled; limited compres-
sor operation. If this
operation is not possi-
ble, the compressor
shuts down after a few
minutes.
■ Energy statement (see
page 91) will not be
calculated correctly.
54
Cause
Communication fault with
EEV controller (refriger-
ant circuit control).
Communication fault with
EEV controller (refriger-
ant circuit control), heat
pump 2nd stage (if instal-
led).
Measures
Check KM BUS connec-
tion. A fluctuating DC volt-
age between approx. 20 V
and 30 V can be meas-
ured at the KM BUS con-
nection to the EEV at the
controller and sensor PCB
(see page 172) across
terminals X5.14 and
X5.15.
Check leads/cables;
check power supply to
EEV controller PCB (see
page 178); replace PCB if
required.
Check KM BUS connec-
tion. A fluctuating DC volt-
age between approx. 20 V
and 30 V can be meas-
ured at the KM BUS con-
nection to the EEV at the
controller and sensor PCB
(see page 172) across
terminals X5.14 and
X5.15.
Check leads/cables;
check power supply to
EEV controller PCB (see
page 178); replace PCB if
required.