Omega OTEC IEWB Series - P7 IDU Anti-Frosting Protection; P8 High IPM Temperature Protection

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Phase sequence error protection
L7
Compressor stall fault
L8
Possible reason:
 Wrong wire connection
 IPM malfunction
 Compressor malfunction
 Faulty PCB
Troubleshooting and repair:
a) Check the wiring between PCB and compressor.
b) Check the outdoor unit fan and ventilation.
c) Check the IPM in PCB.
d) Check the resistance of compressor.
e) If all are normal, change a new PCB.
2.4.20 P7 IDU anti-frosting protection
Description: indoor unit evaporator temperature T2 is lower than 0℃.
Possible reason:
 Filter or evaporator is dirty
 Indoor fan motor can’t work normally or the flap is closed
Troubleshooting and repair:
a) Clear the filter and evaporator
b) Check the fan motor
2.4.21 P8 High IPM temperature protection
Description: the detected temperature of IPM is higher than 100℃.
Possible reason:
 Power supply issue
 System leakage or block
 Faulty outdoor unit PCB
 Connection problem
Troubleshooting and repair:
d) Check the power supply.
e) Check the fastening screws on the PCB and IPM radiator. If they are not fixed tightly, tighten the
screws and apply silicon grease. Otherwise, go to next step.