Corrective Action - Viessmann Vitocrossal 300 Service Manual

Troubleshooting

Corrective Action

86
Temperature
Vitocrossal 300 CU3A 26 to 57 Service
Accessing the Control Electrical Connections Box
1. Remove the screws from the top panel and set aside.
2. Slide the top panel to the rear of the boiler and lift up.
3. Remove the retaining nuts from the control
connection cover and set aside.
4. Slide the control connection cover to the rear of the
boiler and lift up.
Checking the outdoor temperature sensor
1. Pull plug "X3" from the control unit.
2. Test the resistance of the outdoor temperature
sensor across terminals "X3.1" and "X3.2" on the
disconnected 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
outdoor temperature sensor. Sensor type: NTC 10 kΩ