Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 142

Troubleshooting
Messages
(cont.)
Message
System characteristics Cause
C2 Power supply monitor
C5 Power-OFF
C9 Refrigerant circuit
142
Compressor power sup-
ply fault or phase monitor
faulty
Power-OFF enabled
(triggered by power sup-
ply utility)
Refrigerant circuit fault,
heat pump stage 1
(type BW):
■ Safety high pressure
switch has responded.
■ Compressor motor
protection (thermal
relay) has responded
■ Klixon start-up resistor
■ If supplied:
Separate compressor
motor protection has
responded
Measures
Check connections,
phase connection and
power supply; check
phase monitor.
The switching signal can
be tested at connection
215.2.
No measures required.
If message persists:
Check the cross connect
PCB connections first at
terminal X3.7 (feed) then
at terminal X3.6
(230 V~).
■ Check flow and return
temperature sensors in
primary and secondary
circuits.
■ Check primary and sec-
ondary circuits for pres-
sure and throughput
(see also message A9).
■ Have heat pump tested
by a refrigeration engi-
neer.
The switching signal can
be tested at connection
215.4.
Note
After removing fault,
switch appliance OFF and
ON again once.