Haier 2U40S2SM1FA, Service Manual, Page: 44 / 73

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.4.7 The communication fault between IPM and outdoor PCB
Outdoor display: LED1 flash 4 times
Method of Communication is detected by checking the IPM module and the outdoor PCB
Malfunction
Detection
Malfunction The outdoor PCB broken leads to communication fault
Decision The IPM module broken leads to communication fault
Conditions
Supposed The outdoor PCB is broken
Causes The IPM module is broken
Communication wiring disconnected
Troubleshooting * Caution Be sure to turn off power switch before connect or disconnect connector, or
else parts damage may be occurred.
1) Check whether Terminal CN22 and CN23 on the outdoor mainboard
CN10 and CN11 on IPM module
2) Check whether the connected wire between IPM and outdoor
Are they good?
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,
Replace the outdoor mainboard with a new one
Replace the outdoor IPM module
with a new one.
YES
NO
NO
YES
Malfunction unsolved
1) Pull out and reinsert the terminals.
2) Replace connected wire
Service diagnosis
Domestic air conditioner
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