Bosch IDS 2.0 - PH Troubleshooting

Service Manual Bosch IDS 2.0 | 57
Bosch Thermotechnology Corp. | 07.2021
Data subject to change
12.3.16 PH Troubleshooting
LED display output: PH
Description: Low discharge superheat protection.
Possible causes:
 Poor heat exchange on coil (cooling mode – indoor coil, heating mode – outdoor coil)
 Fan motor failure (cooling mode – indoor fan, heating mode – outdoor fan)
 Service valves not open
 TXV/EEV/filter drier blocked
 Under charged
Table 44
Procedure:
Figure 31
Are you running in
force mode?
Ye s
Ye s
Is there still a fault
code?
Is ambient
temperature >
120F?
No
Ye s
Quit force mode
No
Ye s
Is the system
under charged
Ye s
Follow IOM to adjust
refrigerant
No
Did T3/T5 sensor
fail 
Ye s
Replace T3/T5
No
Restart system
Check for abnormal
pressure 
No
No service required
1) See Section 13.1
2) See Section 13.4