Haier MRV 5 Series Troubleshooting Manual page 189

Method3.
Only connect indoor1- indoor4,
if OK,means indoor1- indoor4 OK
Note: for above operation, each time
you need to re-power and then
search quantity of and lock the
indoor units
Check and connect the "faulty" unit
by a different temporary P-Q cable
just to make a test; sometimes the
problem could be on the cable.
Only connect indoor1- indoor6,
if OK, means indoor1- indoor6 OK
Only connect indoor1- indoor7,
alarm, means there is
a problem with indoor7
If the cable no problem, replace the PCB
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