Toshiba MMU-P0121H Service Manual page 79

<For 4-way Air Discharge Cassette type>
Check code
[99]
Indoor remote controller
communication alarm
Are A, B, C inter-unit
wires normal?
YES
Is there a disconnection
or connection error?
NO
Is group operation performed?
NO
Is the unit set up No.1?
YES
Does the indoor unit operate?
YES
1. Remote controller circuit connection error
2. Duplicated indoor No.1 units
3. Remote controller error
4. Indoor main P.C. board (MCC-1361) failure
NO
YES
YES
Is unit set up No.1
included in the indoor units
under group operation?
YES
Is unit set up No.1 duplicated?
NO
NO
NO
Does serial send LED (Green)
D11 from remote controller on indoor
main P.C. board (MCC-1361) flash?
YES
Does serial receive LED (Orange)
D13 from remote controller on indoor
main P.C. board (MCC-1361) flash?
NO
3-76
Operation cause
Modify connection of wiring.
Check indoor main
P.C. board (MCC-1361).
Defective
NO
Set 1 unit to unit set up No.1.
YES
Avoid duplication of unit
set up to No.1.
Make unit set up No.1.
Check indoor main
NO
P.C. board (MCC-1361).
Defective
YES
Check remote controller P.C. board.
Defective Replacement
Replacement
Replacement