Viessmann Vitocrossal 300 Service Manual page 88

Troubleshooting
Corrective Action
Temperature sensors
88
(continued)
Vitocrossal 300 CU3A 26 to 57 Service
Checking the flue gas temperature sensor
The flue gas temperature sensor locks out the boiler
when the permissible flue gas temperature is exceeded.
Reset the interlock after the flue system has cooled
down by pressing reset button R.
1. Pull the leads from flue gas temperature sensor A.
2. Check the sensor resistance and compare it with
the curve.
3. Replace the sensor in the case of severe deviation.
Checking the boiler fuse
1. Switch off the power.
2. Remove top panel and cover (see page 86).
3. Check fuse F1 (see connection and wiring diagram).