Mitsubishi Electric MUZ-AP VG Series Service Manual page 31

2. Table of indoor unit failure mode recall function
NOTE: Blinking patterns of this mode differ from the ones of TROUBLESHOOTING CHECK TABLE (10-4.).
The upper lamp
Abnormal point
of OPERATION
(Failure mode)
INDICATOR lamp
Not lit Normal
1-time blink every Room temperature
0.5-second thermistor
Indoor coil
2-time blink
2.5-second OFF
thermistor
3-time blink
Serial signal
2.5-second OFF
11-time blink
Indoor fan motor
2.5-second OFF
12-time blink Indoor control
2.5-second OFF system
OBH788C
Condition
—
The room temperature thermistor short or
open circuit is detected every 8 seconds dur-
ing operation.
The indoor coil thermistor short or open circuit
is detected every 8 seconds during operation.
The serial signal from outdoor unit is not re-
ceived for a maximum of 6 minutes.
The rotational frequency feedback signal is
not emitted for 12 seconds after the indoor fan
motor is operated.
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
Refer to the characteristics of the room temperature
thermistor (10-7.).
Refer to the characteristics of the main indoor coil ther-
mistor, the sub indoor coil thermistor (10-7.).
Refer to 10-6.
signal error".
Refer to 10-6.
Replace the indoor electronic control P.C. board.
31
Remedy
—
"How to check miswiring and serial
"Check of indoor fan motor".