Bosch IDS BOVB60-20 - Troubleshooting Fault Codes PH and LO-L9

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Installation Instructions
Bosch IDS BOVB20 Split System Heat Pump - BTC 761701316 C (02.2022)
WARNING: HAZARDOUS VOLTAGE
 When measuring resistance , make sure the unit is powered
off and wait 3 min before taking measurement.
Figure 71
PH (Low discharge superheat protection)
Restart System
Is the
resistance of T5
in range of Table
16?
Replace T5 sensor
Are
you running in force
mode?
Quit force mode
Is there abnormal
pressure in the
system?
Are the service valves
open?
Open the service valves
Yes
No
Yes
Yes
No
No
Yes
No
Is the
ambient temperature
>120°F?
Clear any blockage in the
refrigerant,Correct poor
heat exchange (air flow
restriction, motor failure)
Is the system
undercharged?
Adjust refrigerant
No
Yes
Yes
No
Is the
resistance of T3
in range of Table
15?
Replace T3 sensor
No
Yes
Figure 72
L0-L9 (IPM module protection)
Is the power
supply stable?
Does the
unit run normally for
at least 1 hour?
Check
for blockage in EEV,
TXV or Filter Drier
Is the compressor
operating normally?
Correct the
power supply
Remove blockage
Replace
compr esso r
Power off and wait 3 minutes
before powering on
Check the
refrige rant charg e
Replace
compr esso r
Replace control board
Are the service valves
open?
Open the
service valves
Yes
No
Yes
No
Yes
No
Yes
No
No
Yes
Yes
No
Is
there any
abnormal noise from
the compressor?