Viessmann Vitotwin 300-W Installation And Service Instructions For Contractors page 139

Repairs
(cont.)
Checking the outside temperature sensor
A
B
A Outside temperature sensor
B Junction box
1 2 3 4
ATS B42/
B10
200
100
80
60
40
20
10
8
6
-20 -10 0
Temperature in °C
Sensor type: NTC 10 kΩ
1. Pull plug "2K" from the control unit.
2. Test the resistance of the outside
temperature sensor at 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.
Troubleshooting
10 20 30
139