Bosch Climate 5000 Series Service Manual page 50

Service Manual
7.6.5 Open circuit or short circuit of temperature sensor diagnosis and
solution (EC 52/EC 53/EC 54/EC 56/EH 60/EH61)
Error Code
Malfunction decision conditions
Supposed causes
Table 33
Troubleshooting:
Figure 46
Figure 47
5 0 |
EC 52/EC 53/EC 54/EC 56/EH 60/EH61
If the sampling voltage is lower than 0.06V DC or higher than 4.94V DC, the LED will display the failure.

Wiring mistake

Sensor faulty

Indoor / Outdoor PCB faulty
Check the connection
between temperature
sensor and PCB.
Yes
Measure the resistance value
of the sensor and compare to
the values in Appendix 1
(pg.83) and Appendix 2
(pg.84). Does the reading
agree with the table?
Yes
Replace indoor or outdoor
main PCB
Bosch Wall Mounted Ductless Split Air Conditioner / Heat Pump IDU-ODU - BTC 769102301 A (11.2022)
No Correct the connection
No Rep a l ce the sensor
Some models, PCB could not removed separately, then entire outdoor
electric control box should be replaced.
For certain models, outdoor unit uses combination sensor, T3,T4 and TP
are the same of sensor.