Viessmann Vitocal 300-G Installation And Service Instructions Manual page 129

Control unit diagnostics
ID Message
(priority)
CA Primary
source ("U")
CB Primary tem-
perature ("i")
CC Coding card
("U")
CD KM BUS
Vitocom ("U")
CE KM BUS Ext.
AE ("U")
D1 Compressor
("U")
D3 Low pressure
("!")
(cont.)
1. Cause
2. Measures
1. The monitoring primary source input
has responded (brine pressure, flow
meter)
2. Check safety equipment (frost pro-
tection brine pressure, frost protec-
tion AC-Box) on terminals 3X3.9 and
3X3.8;
(frost protection brine pressure, frost
protection AC-Box) check jumper
across 3X3.9 and 3X3.8
1. Min. primary inlet temperature not
achieved
2. Check the brine circuit for flow rate
1. The coding card cannot be read
2. Check the coding card and replace,
if required
1. Fault KM BUS Vitocom 100
2. Check connections and connecting
cables
1. Fault KM BUS external extension H1
2. Check connections and connecting
cables
1. Thermal compressor relay or safety
element of the full wave soft starter
(if fitted) has responded
2. Reset the thermal relay, check the
setting, perform a "reset", check the
connection, check the coil resis-
tance, adjust the phase sequence at
the compressor
1. Inadequate circulation volume in the
primary circuit; air in the brine/pri-
mary circuit or heat pump faulty;
faulty pressure sensor
2. Pressure switch resets itself automa-
tically, check primary pump and
shut-off facilities; have a refrigera-
tion engineer check the heat pump
Troubleshooting
Access
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