Haier AS25THMHRA-C Service Manual page 190

10.3.7 The communication fault between IPM and outdoor PCB
Outdoor display:
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
Troubleshooting * Caution Be sure to turn off power switch before connect or disconnect connector,
parts damage may be occurred.
1) Check whether Terminal CN23 and CN24 on the outdoor mainboard
CN10 and CN11 on IPM module
2) Check whether the connected wire between IPM and outdoor
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
LED1 flash 4 times
Communication wiring disconnected
Are they good?
YES
NO
NO
1) Pull out and reinsert the terminals.
2) Replace connected wire
Malfunction unsolved
YES
36
Service diagnosis
Replace the outdoor IPM module
with a new one.
Domestic air conditioner
or else