York IDM030B21E Series Service Manual page 43

No
Is LED1 (red) on
Change-Over Box
PCB ON?
Yes
Yes
Is LED3 (green) on
Change-Over Box
PCB ON?
No
Is LED2 (yellow) on
No
Change-Over Box PCB
flashing more than
once in 10 seconds?
Yes
Yes
Is LED3 (yellow)
on I.U. PCB ON?
No
Is LED3 (yellow) on
I.U. PCB flashing more
than once in 10 seconds.
Yes
Does refrigerant system
No. setting between
O.U. and I.U correspond?
( )
O.U.: DSW4 and RSW1
I.U.: DSW5 and RSW2
Yes
Does Alarm occur with
all indoor units?
Yes
Faulty O.U. PCB.
SM-16005-rev.2
Is voltage between
"L1" and "N" of PCN1
on Change-Over Box
PCB 208 or 230V?
Yes
Is the fuse for
Change-Over Box
PCB blown?
No
Is LED3 (yellow)
ON even if connector
CN2 on I.U. PCB
is removed?
No
No
No
No
O.U. PCB: Outdoor Unit PCB
I.U. PCB: Indoor Unit PCB
No
Check Change-Over
Box wiring.
Yes
Replace fuse.
Faulty Change-Over
Box PCB.
Check other
Change-Over Boxes.
Check wiring between
outdoor unit and indoor
units.
Yes
Faulty I.U. PCB.
Check other indoor units.
Check wiring between
outdoor unit and indoor
units or fuse (EF) for
I.U./O.U. PCB.
Set it correctly.
Faulty I.U. PCB.
TROUBLESHOOTING
Change-Over
Box
(In Case
of Heat
Recovery
System)
Indoor
Unit
3-21