Carrier 538FEQ009RBGA, Service Manual

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2. IPM protection (H5), de--synchronizing malfunction (H7), over--current of compressor phase current (P5) (AP1 below means control board of
the outdoor unit).
Main detection points:
S Is voltage input within the normal range?
S Is the control board AP1 connected with the compressor
comp?
S Are the connections tight?
S Is the connection sequence correct?
S Heat exchange of unit is blocked (heat exchanger is dirty).
S Is the system pressure too high?
S Is the refrigerant charging amount correct?
S Is the coil resistance of compressor normal?
Malfunction diagnosis process:
N
H5, H7 or P5 is
displayed after
turning on the unit
Measure if the voltage
input is within 180~265V
with AC voltmeter
(see fig 30)
The compressor
is connected
with mainboard
AP1?
Heat exchanger is
blocked with dirt?
Clean the heat exchanger
to improve its performance
Restart the unit
Restart the unit
Restart the unit
Restart the unit
The unit starts
operation again
The unit starts
operation again
The unit starts
operation again
The unit starts
operation again
Repair power supply
Check if system pressure
is too high?
Adjust refrigerant
charging amount
Replace outdoor
mainboard AP1
Replace compressor
Does the unit
work normally
End
Adjust it properly
according to wiring
diagram 5.1
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Fig. 31 – Troubleshooting