Mitsubishi Electric TRANE NTXFKS09A112AA Service Manual page 33

LED indication
for communication status
Communication status is indicated
by the LED.
Unit status
Blinking: normal communication
Lighting: abnormal communication or
not connected
Pattern 1 and 2 is repeatedly displayed
alternately. Each pattern is displayed for
15 seconds.
NOTE: "Lighting" in the table below does not
indicate abnormal communication.
Outdoor control P.C. board
LED1 LED2 LED3
Blinking
Pattern
LED 1 LED 2
Unit A Unit B
1
status status
Unit C
Unit D
2
status status
Unit E
3
status
OBHT752
C
Turn ON the power supply.
Does the LED on the outdoor control P.C.
board repeat "3.6-second-OFF
and 0.8-second-ON quick blinking"?
Turn OFF the power supply.
Remove the bridge between
outdoor terminal block S2 and S3.
Turn ON the power supply.
Is there amplitude of 10 to 20 VDC
between outdoor terminal block S2
and S3? <Confirmation of serial
signal>
LED 3
Lit
Is there rated voltage between
Not lit
indoor terminal block S1 and S2?
Blinking <Confirmation of power voltage>
Yes
Replace the indoor electronic control P.C. board.
Be sure to release the failure-mode
recall function after checking.
No
Replace the outdoor control P.C. board.
(Lit or
not lit)
Yes
No
Yes
Is there any error of the
indoor/outdoor connecting wire,
such as the damage of the wire,
intermediate connection, poor
contact to the terminal block?
No
33
2
2 Be careful of the residual
voltage of smoothing capacitor.
Replace the
Yes
indoor/outdoor
connecting wire.
No