Viessmann VITOTRONIC 200 Service Instructions Manual page 174

Diagnosis
Refrigerant circuit
Message Meaning
code
3A Safety high pressure
S
switch has responded.
4A Evaporation temperature
―
too low
4B EEV connecting cable
S
■
faulty
EEV stepper motor faul-
■
ty
56 Condenser frost risk
H
60 DHW heating via auxiliary
S
heat exchanger fault
61 Fan fault
S
62 Flow switch does not de-
S
tect a flow rate.
63 Lower outside tempera-
H
ture limit not reached
66 Motor overload relay or
S
safety equipment at the
soft starter has respon-
ded.
174
(cont.)
Heat pump characteris-
tics
Both compressors OFF
Compressors remain op-
erational.
Both compressors OFF
Both compressors OFF
■
Refrigerant circuit rever-
■
sal OFF
DHW heating is stopped.
Compressor runs on for
max. 5 min.
Both compressors OFF
Compressor off. The other
compressor may remain in
operation.
Measure
As for "C9 Refrigerant circ (SHD)":
See "Message overview" for the heat
pump control unit.
Check fan.
■
Check evaporator for ice formation.
■
Check evaporator temperature sen-
■
sor: See message code "09".
Check the EEV connecting cable.
■
Replace the connecting cable if nec-
essary.
Replace EEV.
■
Check hydraulics in the secondary
■
circuit, e.g. whether all shut-off
valves are fully open.
Check secondary circuit flow rate.
■
Check flow and return temperature
■
in the secondary circuit.
Check secondary circuit flow tem-
■
perature sensor in the appliance.
Check refrigerant charge. Adjust if
■
necessary.
Check temperature sensors in the
■
refrigerant circuit.
Check auxiliary heat exchanger flow
■
rate.
Check circulation pump for cylinder
■
heating.
Check cylinder loading pump.
■
Check if fan is blocked.
■
Carry out mechanical check of fan.
■
Check fan control or PWM signal at
■
the controller PCB: See "Controller
PCB and EEV PCB [6]".
Check secondary circuit flow rate.
■
Check secondary pump.
■
Test voltage at the controller PCB con-
nection: See "Controller PCB and EEV
PCB [6]".
0 V: Flow switch has responded.
■
230 V~: Flow switch has not respon-
■
ded.
No action required
Check soft starter. Check status in-
■
put at the controller PCB: See "Con-
troller PCB and EEV PCB [6]".
Check motor currents/motor over-
■
load relay.