Viessmann VITODENS 200-W Service Instructions Manual page 110

Troubleshooting
Repairs
(cont.)
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Temperature in °C
1. Pull plug "X3" from the control unit.
110
2. Test the resistance of the outside
temperature sensor across terminals
"X3.1" and "X3.2" on the disconnec-
ted plug and compare it with the
curve.
3. Where actual values deviate severely
from the curve values, disconnect the
wires at the sensor and repeat test on
the sensor itself.
4. Subject to result, replace the lead or
the outside temperature sensor.