Viessmann VITOTRONIC 200 Service Instructions Manual page 63

Messages
(cont.)
Message
Code/system characteris-
tics
D4 Control high pressure
Compressor stops.
D6 Flow switch
Compressor stops.
Cause
High pressure fault:
■ Air in heating circuit.
■ Secondary pump or
heating circuit pump
blocked.
■ Condenser contamina-
ted.
■ High pressure sensor
faulty.
Well circuit flow switch
does not detect flow
rate.
Troubleshooting
Measures
■ Vent heating circuit.
■ Check system pres-
sure.
■ Check secondary pump
and heating circuit
pumps.
■ Flush heating circuits.
Note
In rare cases, e.g. during
DHW heating, a high pres-
sure fault can occur.
If this occurs several times
in succession, check the
heat pump and parameter
settings of the refrigerant
circuit.
■ Check well pump.
■ Check primary circuit.
■ If no flow switch is
installed, insert a
jumper across X3.3/
X3.4 (see page 165).
The signal can be tested
at terminal 216.3 (see
page 150) or across ter-
minals X3.3/X3.4.
63