85
Checking the outside temperature sensor
X3
Fig. 56
1.
Disconnect plug "X3" from the control unit.
2.
Test the resistance of the outside temperature sen-
sor across terminals "X3.1" and "X3.2" on the dis-
connected plug and compare it with the curve.
100
10
-20 -10 0
10 20 30
Temperature in °C
6
8
20
40
60
80
200
Resistance
in kΩ
Fig. 57
Sensor type: NTC 10 k
Ω
3.
In the event of severe deviation from the curve,
disconnect the wires at the sensor and repeat the
test on the sensor itself.
4.
Depending on the test result, replace the lead or
the outside temperature sensor.
Checking the boiler water temperature sensor or cylinder temperature sensor
5
Fig. 58
1.
■
Boiler water temperature sensor: Disconnect
leads from boiler water temperature sensor
A
and check the resistance.
■
Cylinder temperature sensor: Disconnect plug
%
from the cable harness at the control unit and
check the resistance.
2.
Check the sensor resistance and compare it with
the curve.
10
1
10 30 50 70 90 110
Temperature in °C
0.4
0.6
0.8
2
4
6
8
20
Resistance
in kΩ
Fig. 59
Sensor type: NTC 10 k
Ω
Troubleshooting
Repairs
6136330
Service
