Toshiba MMU-AP0091H service manual 153, L18 / 8A Flow selector unit system error, L20, L28

Check code Check code name Cause of operation

[L18] / [8A]		Flow selector unit system error		An indoor unit which has been operated in
(TCC-L / AI-NET)				cooling only mode is operated in heating mode
				without setup for cooling only mode.
Is every indoor unit been			NO		Set up All cooling mode.
					Item code (DN)=OF
set up for cooling only mode?
					Cooling only operation mode=0001
	YES
					Check flow selector unit.

Check code	Check code name		Cause of operation
[L29] / [CF]	IPDU quantity error	1.	Incorrect model setup in service for I/F P.C.
(TCC-L / AI-NET)			board
		2.	Communication error between IPDU, fan
			IPDU and I/F
		3.	IPDU, fan IPDU, I/F P.C. board error
Sub-code:
01: IPDU1 error	02: IPDU2 error
03: IPDU1, 2 error	04: Fan IPDU error
05: IPDU1, fan IPDU error	06: IPDU2, fan IPDU error

07: All IPDU error or disconnection of communication line between IPDU-I/F P.C. board or outdoor I/F P.C. board error

Check code	Check code name	Cause of operation
[L20] / [98]	Duplicated central	Central control addresses are duplicated.
(TCC-L / AI-NET)	control addresses

Is jumper setup of outdoor I/F P.C. board correct?		NO
(Jumpers 7, 8, 9 ON)
	YES
		YES
Is communication connector between
IPDU and I/F P.C. board connected?
	NO

Correct connection.

Correct connection.

Are two or more	YES
central control system with identical
network addresses connected?
NO

153

Correct the network address of the central control system.

Check the network adaptor on the indoor P.C. board.

Is the communication line between		YES
IPDU and I/F P.C. board disconnected?
	NO
Is there voltage fluctuation between		NO
pin 4 and pin 5 of CN600 on I/F P.C. board
(measure by tester: DC 0 to 5 V).
	YES

Reconnect communication line.

I/F P.C. board error

Check code	Check code name		Cause of operation
[L28] / [46]	Quantity over of	1.	Quantity over of connected outdoor units
(TCC-L / AI-NET)	connected outdoor units	2.	Connection error of communication line
			between outdoor units
		3.	Outdoor I/F P.C. board error

Is there voltage fluctuation between			NO	IPDU P.C. board error
pin 3 and pin 5 of CN600 on I/F P.C. board
(measure by tester: DC 0 to 5 V).
	YES	Both IPDU (No.1, No.2) and fan IPDU
		did not return the communication.

Is No. of connected		NO	Max. 3 units are allowed for flex system.
outdoor units below 3 units?
	YES
		NO
Is the communication line
			Correct connection of the communication line.
between outdoor units correct?
	YES

Check outdoor I/F P.C. board.

On the fan power supply P.C. board,	NO
1) CN503: Between 1 and 5 pins 12V

2)CN503: Between 2 and 5 pins Æ7V

3)Between +5V and GND at the side of CN505: 5V

YES

Replace IPDU P.C. board with trouble.

Replace fan power supply on P.C. board.

Auxiliary code	P.C. board to be replaced
01	IPDU1
02	IPDU2
03	IPDU1, 2
04	Fan IPDU
05	IPDU1, fan IPDU
06	IPDU2, fan IPDU
07	IPDU1, 2, fan IPDU, I/F