Service Manual Bosch IDS 2.0 | 61
Bosch Thermotechnology Corp. | 07.2021
Data subject to change
12.4.2 System Does Not Start
LED display output: No fault code displayed
Description: High voltage power is available to the unit, unit is given call for heating/cooling, system does not start
Possible causes:
The thermostat is improperly wired
Thermostat not giving call for heating/cooling
Damaged thermostat
Disconnected compressor wiring harness
Table 48
Procedure:
Figure 35
Power off and wait at least 3
minutes before powering on
Check that thermostat is sending call
for heating/cooling
Correct wiring
Yes
No
Is the wiring correct
according to wiring
diagram?
Correct thermostat wire
connection/replace the
thermostat
No
Yes
Is there 18-28VAC
and 0VDC between
Y&C and B&C at
the outdoor unit?
Connect the compressor
wire
Yes
No
Is the compressor
wire disconnected?
Refer to Appendix 1
Correct power supply
No
Yes
Is there 230VAC
power at high
voltage terminal?
If your unit is not starting it may be
due to a designed delay. Check
Notes 1-3.
1) If high voltage power to the unit is interrupted and then restored, the compressor
ALWAYS waits at least 3 mins before it starts via a thermostat Y call, the outdoor
fan motor will always start immediately upon thermostat Y call.
2) In cooling mode: There is at least a 6 minute delay between when the thermostat
is satisfi ed and compressor can turn back on with a Y call.
3) In heating mode: There is at least a 3 minute delay between when the thermostat
is satisfi ed and compressor can turn back on with a Y call.
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