Viessmann VITOCAL 300 Installation And Service Instructions Manual page 61

Control unit diagnostics
Fault messages
A9 Heat pump
AB E heater
AC Natural cooling
Mixer – heating/
AD
DHW
AF Cylinder primary
pump
C1 Power supply/
compressor
C3 Brine pressure
(cont.)
Cause
Heat pump or circula-
tion pump of the pri-
mary or secondary
circuit faulty
The flow temperature
does not rise, the elec-
tric heater may be
faulty or the high limit
safety cut-out has re-
sponded
Faulty function
Three-way valve faulty
Cylinder primary pump
is faulty
Compressor fuse, main
isolator, phase monitor
or motor overload
faulty
Brine pressure too low
Troubleshooting
Measures
Check the heat pump, the
primary pump and the sec-
ondary pump (see page 51),
and replace, if required.
The device enters emer-
gency mode with the electric
heater until the fault mes-
sage has been acknowl-
edged (heating circuits:
reduced mode, set DHW
temperature: 30 °C).
After the repair has been
carried out, the heat pump
only restarts after the equip-
ment was first turned OFF.
Check the electric heater
and the high limit safety cut-
out, possibly reset the high
limit safety cut-out (see
page 63).
As part of the relay test (see
page 79), check the natural
cooling connection exten-
sion and the continuity to the
pumps.
In case of natural cooling
with mixer; check the mixer
motor and the direction of ro-
tation.
Check the three-way valve
(see page 51) and replace, if
required
Check the pump (see
page 51); replace, if required
Check the components and
replace them, if required.
For phase monitor descrip-
tion, see page 127
Increase the pressure in the
primary circuit
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