Haier 1U09BS2ERA - The Communication Fault between Ipm and Outdoor Pcb

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7.4.6 The communication fault between IPM and outdoor PCB 
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Indoor display F3
Outdoor display: LED1 flash 4 time
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Domestic air conditioner
Method of
malfunction
detection
Malfunction
detection
conditions
Communication is detected by checking the IPM module and the outdoor PCB.
ƵThe outdoor PCB broken leads to communication fault
ƵThe IPM module broken leads to communication fault
Supposed
causes
ƵThe outdoor PCB is broken
ƵThe IPM module is broken
ƵCommunication wiring disconnected
Troubleshooting
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Be sure to turn off power switch before connect or disconnect connector, or
else
parts damage may be caused
1) Check whether terminal CN23 and CN24 on the
outdoor PCB CN10 and CN11 on IPM module
2) Check whether the connected wire between IPM
and outdoor is well connected
NO
1) Pull out and reinsert the
terminals.
2) Replace connected wire.
YES
Electrify the machine again and turn
it on, Check whether the voltage between 1 and 2
of Terminal CN23 is about DC5V, Check whether
the voltage between2 and 3 of Terminal CN23 is
about DC15V
.
Malfunction unsolved
YES
NO
Replace the outdoor IPM
module with a new one.
Replace the outdoor PCB with
a new one.