Haier HSU18VHJ(DB) Service Manual page 63

tester)
Normal resistance
Unacceptable resistance
7.3.4 The IPM and outdoor PCB don't communicate or Related Abnormality
outdoor display LED1 flash 4 times
Method of Communication is detected by checking the IPM module and the outdoor PCB
Malfunction
Detection
Malfunction
Decision
Conditions
Supposed
Causes
Troubleshooting * Caution Be sure to turn off power switch before connect or disconnect connector, or
1) Check whether Terminal CN23 and CN22 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 CN22is about DC5V,
Check whether
between2 and 3 of Terminal CN22
is about DC15V,
HSU12/18VHJ(DB)
The outdoor PCB broken leads to communication fault
The IPM module broken leads to communication fault
The outdoor PCB is broken
The IPM module is broken
Communication wiring disconnected
else parts damage may be occurred.
NO
YES
the voltage
NO
NO
Several k to several M ( )
Short (0 ) or open
Indoor Display F3
1) Pull out and reinsert the terminals.
2) Replace connected wire
YES
Replace the outdoor mainboard with a new one
60
Functions and control
Replace the outdoor IPM
module with a new one.
Domestic Air Conditioner