Flow Sensor Secondary - Viessmann VITOTRONIC 200 Service Instructions Manual

Troubleshooting
Message overview

28 Flow sensor secondary

Operation with secondary circuit flow temperature
■
sensor in the appliance (if installed), e.g. with
Vitocal 300-A, type AWO 301.B25 to B60.
or
Operation with temperature value of return tempera-
ture sensor in secondary circuit, plus 5 K.
If the secondary circuit flow and return temperature
■
sensors are faulty at the same time, the message
"A9 Heat pump" appears and the heat pump shuts
down.
Cause
Lead break, secondary circuit flow temperature sensor
29 Return sensor secndry
Operation with temperature value of flow tempera-
■
ture sensor in secondary circuit, minus 5 K.
■ If the secondary circuit flow and return temperature
sensors are faulty at the same time, the heat pump is
switched off. After 24 h the message "A9 Heat
pump" appears.
Cause
Lead break, secondary circuit return temperature sen-
sor
2C Suction gas revers. temp.
■ Heating mode:
Heat pump remains in operation.
Cooling mode:
■
Compressor stops.
Cause
Lead break, reversible suction gas temperature sensor
2D Liquid gas temp sensor
Compressor stops.
Cause
Lead break, liquid gas temperature sensor
80
(cont.)
Measure
Check resistance value (Pt500A) at plug F8 or at termi-
nals X25.9/X25.10: See "Controller and sensor PCB".
Measure
Check resistance value (Pt500A) at terminals X25.11/
X25.12: See "Controller and sensor PCB".
Measure
Check resistance value (Pt500A) at terminals X25.15/
X25.16: See "Controller and sensor PCB".
Measure
Check resistance value (Pt500A) at terminals X25.17/
X25.18: See "Controller and sensor PCB".