Toshiba MMU-AP0121MH, MMU-AP0181MH E20, E23, E25, E26, ∗ 1 How to clear the error, E28

Check code	Check code name	Cause of operation
[E20]	Unit connected to other line	When starting automatic indoor address, a
	during automatic address	device in other line is connected.

Auxiliary code : 01: Connection of outdoor in other line 02: Connection of indoor unit in other line

Separate the wire between lines according to address setup method.

Check code	Check code name		Cause of operation
[E23]	Communication sending error	1. Inter-unit cable connection error between
	between outdoor units		outdoor units
		2.	Communication connector connection error
			between outdoor units, I/F P.C. board error
		3.	End terminal resistance setup error between
			outdoor units

Check code	Check code name	Cause of operation
[E25]	Duplicated address setup of	Addresses are duplicated by manual setting of
	terminal outdoor units	outdoor address

Never set up the outdoor address manually.

Check code Check code name Cause of operation

[E26]	Decrease of connected	1. Outdoor unit backup setup
	outdoor units	2.	Outdoor power error
		3.	Communication line connection error between
			outdoor units
		4.	Connector connection error for communication
		5.	Outdoor I/F P.C. board error

Auxiliary code : No. of outdoor units which received signals normally

YES

Is there no miscabling or

disconnection on communication line

between outdoor units? (1)

NO

YES

NO

Correct communication line.

Is outdoor unit setting backup?

NO

NO

Is main power of follower unit turned on?

YES

Clear the error, and then start operation. (*1)

Turn on the main power supply.

69

Is connection of CN03 connector on outdoor I/F P.C. board normal?

YES

Correct cabling of cable connector.

Is communication line between

outdoor units connected normally?

YES

Is communication connector (CN03)

NO	Correct connection of communication line.
NO
	Correct connector connection.

Is not main power of

outdoor unit turned off?

NO

Is the end terminal resistance

between outdoor units turned on?

(SW30 Bit 1)

YES

Turn on main power of outdoor unit.

NO

Turn the end terminal resistance to ON.

between follower outdoor units connected?

YES

Check I/F P.C. board.

(Communication connector: CN03)

(∗ 1) How to clear the error

Set SW01/SW02/SW03 on I/F P.C. board of header unit to 2/16/1, and push SW04 for 5 seconds or more. (7-segment display: [Er.] [CL])

YES

Did power failure occur?

NO

Is there no noise source, etc?

NO

Check outdoor I/F P.C. board.

Defect Replace

YES

Clear check code.

YES

Check and eliminate noise, etc

(∗ 1) In this model, only one outdoor unit is provided to one refrigerant line. Be sure to check there is no communication connection with outdoor unit in the other refrigerant line.

•In this model, only one outdoor unit is provided to one refrigerant line. Be sure to check there is no communication connection with outdoor unit in the other refrigerant line.

Check code	Check code name	Cause of operation
[E28]	Terminal outdoor unit error	Terminal unit error

Auxiliary code : Detected outdoor unit number

SAn error occurred on the terminal unit. Confirm the check code of the terminal unit using 7-segment display on the I/F P.C. board of the terminal unit and check it according to the diagnostic procedure for each check code.

<How to specify the terminal outdoor unit on which error occurred>

Under condition that [E28] is displayed on the 7-segment display of the header unit, when pushing SW04 for 1 second or more, the fan of the outdoor unit which stopped due to the error rotates. If pushing SW05 alone, fan running is released.