Repairs - Viessmann VITODENS 333-F WS3A Service Instructions Manual

Troubleshooting

Repairs

Checking the outside temperature sensor (weather-compen-
sated control unit)
82
1. Pull plug "X3" from the control unit.
2. Test the resistance of the outside
temperature sensor across term-
inals "X3.1" and "X3.2" on the dis-
connected plug and compare it with
the curve.
3. Where actual values strongly devi-
ate from the curve values, discon-
nect the wires at the sensor and
repeat test immediately at the sen-
sor.
4. Subject to result, replace the lead
or the outside temperature sensor.