Repair - Viessmann VITOLADENS 300-W Installation And Service Instructions Manual

Troubleshooting

Repair

Checking the outside temperature sensor (weather-compensa-
ted control unit)
X3
200
100
80
60
40
20
10
8
6
-20 -10 0
Temperature in °C
Sensor type: NTC 10 kΩ
104
10 20 30
1. Pull plug "X3" from the control unit.
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. Depending on the result, replace the
lead or the outside temperature sen-
sor.