P4 ( Compressor Discharge Sensor(T5) Is Seated Fault); E4 ( Temperature Sensor Fault(T3, T4, T5, Tf)); Ph ( Low Discharge Superheat Protection); H8 ( Pressure Transducer(Pt) Fault) - Bosch BOVA Series Installation Instructions Manual

3 0 | Bosch IDS BOVA

P4 ( Compressor discharge sensor(T5) is seated fault)

Diagnosis
Check whether the service
valves are open
Yes
Check whether the T5 is normal
according to Table 2(between
temperature and resistance)
Yes
Check whether the charge is
correct by subcooling
according to installation guide
in charge mode when cooling
Yes
Check whether the compres-
sor is normal (abnormal noise,
abnormal vibration)
Yes
Check whether the EEV is
normal for throttle when heating
(wire seated .coil)
Yes
Figure 51
Error Code Description
PH Low discharge superheat protection
Table 17

PH ( Low discharge superheat protection)

Diagnosis
Check whether T3/T5 are
normal according to Table1,
Table 2
Yes
Check whether the pressure
transduce is measuring properly
th th
from the 8 or 11 data of check
when cooling(from the 9 th or 12
data of check when heatling)
Yes
Check whether indoor unit is
normal by filter, airflow(motor),
and coil(be blocked up) when
cooling
Yes
Check whether the suction
superheat is correct in cooling
Check whether the outdoor
fan is correct and outdoor
coil is blocked in heating
Yes
Figure 52
Data subject to change
Handling
No
Open the service valve
No
Replace the T5 sensor
No
Adjust the charge
No
Replace the compressor
Re-power and check
No
again,if the same, replace
the EEV
Handling
No
Replace fault sensors
No
Replace the pressure
transducer
th
No
Exclude indoor unit fault
reasons and restart
1.Not applicable for piston
No
2.Adjust(close) the TXV superheat
3.To further adjust to SW4-4"on
1. Exclude outdoor unit fault
No
reasons and restart
2. Ensure the reserving coil is
seated well
Error Code Description
E4 Temperature sensor fault(T3, T4, T5, TF)
H8 Pressure transducer(PT) fault
F1 High pressure switch(HPS) fault
Table 18

E4 ( Temperature sensor fault(T3, T4, T5, TF))

Diagnosis
Check whether sensor
T3/T4/T5/Tf are seated and
normal (T4 for Heat Pump only)
Yes
Unplug the sensor, Check
whether the resistance of
T3/T4 is in the range of Table 1
Yes
Unplug the sensor, Check
whether the resistance of T5/Tf
is in the range of Table 2
Yes
Check whether the display the
same error code when
re-powered on
Yes
Figure 53

H8 ( Pressure transducer(PT) fault)

Diagnosis
Check whether pressure
transducer(PT) wiring are
seated and normal
Yes
Check whether the pressure
transduce is measuring
properly from the 8 th or 11
data of check when cooling
Yes
Check whether there is the
same fault
Yes
Figure 54
Installation Instructions
Handling
No
Reseat the sensor
according to wiring diagram
No
Replace the fault T3/T4
sensor
No
Replace the fault T5/Tf sensor
No
Keep running
Handling
No
Wiring according to the
diagram correctly
No
Replace the pressure
transducer
th
No
Keep running
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