Mitsubishi Heavy Industries MHI FDU71VNXVF1 Technical Manual page 274

2.11 MAINTENANCE DATA
2.11.1 Diagnosing of microcomputer circuit
(1) Selfdiagnosis function
(a) Check Indicator Table
Whether a failure exists or not on the indoor unit and outdoor unit can be know by the contents of remote control error
code, indoor/outdoor unit green LED (power pilot lamp and microcomputer normality pilot lamp) or red LED (check
pilot lamp).
(i) Indoor unit
Remote control Indoor control PCB
Error code Red LED Red LED
Stays OFF
No-indication Stays OFF Stays OFF Stays OFF
*
3 times
flash
or
WAIT
Stays OFF
INSPECT I/U
Stays OFF
2 times
flash
2 times
flash
2 times
flash
1 time flash
1 time flash
Keeps
flashing
1 time flash
1 time flash
Stays OFF
1(2) time
flash
1 time flash
1(2) time
flash
Stays OFF
Note (1) Normal indicator lamp (Indoor, outdoor units: Green) extinguishes (or lights continuously) only when CPU is anomalous. It keeps
flashing in any trouble other than anomalous CPU.
(2) * mark in the Description of trouble means that, in ordinary diagnosis, it cannot identify the cause definitely, and, if the trouble is repaired by replacing
the part, it is judged consequently that the replaced part was defective.
Outdoor control PCB
Location of
Green Green
trouble
Red LED
LED (1) LED (1)
Keeps Keeps
Stays OFF —
flashing flashing
2 times
Indoor unit power
Stays OFF
supply
flash
Remote control
wires
Keeps Keeps
Stays OFF
flashing flashing
Remote control
Indoor-outdoor
units connection
Keeps 2 times Keeps
wire
flashing flash flashing
Remote control
Remote control
*
wires (Noise)
Keeps Keeps
Stays OFF
flashing flashing
Remote control
indoor control PCB
Indoor-outdoor
Keeps 2 6 times Keeps
units connection
flashing flash flashing
wire
(Noise)
Keeps Keeps
Stays OFF
flashing flashing
Outdoor control
PCB
Outdoor control
Keeps
PCB
Stays OFF Stays OFF
flashing
Fuse
Indoor heat
exchanger tempera-
Keeps Keeps
ture thermistor
Stays OFF
flashing flashing
Indoor control PCB
Indoor return air
temperature therm-
Keeps Keeps
istor
Stays OFF
flashing flashing
Indoor control PCB
Installation or oper-
ating condition
Indoor heat
Keeps Keeps
Stays OFF exchanger tempera-
flashing flashing
ture thermistor
Indoor control PCB
Drain trouble
Float switch
Keeps Keeps
Stays OFF
flashing flashing
Indoor control PCB
Option
Keeps Keeps Number of con-
Stays OFF
flashing flashing nected indoor units
Fan motor
Keeps Keeps
Stays OFF
flashing flashing
Indoor power PCB • Defective indoor power PCB
Keeps Keeps
Stays OFF Indoor control PCB • Improper operation mode setting
flashing flashing
Fan motor
Keeps Keeps
Stays OFF
flashing flashing
Indoor power PCB • Defective indoor power PCB
Keeps Keeps Remote control tem-
Stays OFF
flashing flashing perature thermistor
Description of trouble
• Normal operation
• Power OFF, broken wire/blown fuse, broken transformer wire
• Poor connection, breakage of remote control wire * For wire breaking at power ON, the
LED is OFF.
• Defective remote control PCB
• Poor connection, breakage of indoor-outdoor units connection wire
• Improper setting of master and slave by remote control
• Poor connection of remote control signal wire (White)
* For wire breaking at power ON, the LED is OFF
• Intrusion of noise in remote control wire
*
• Defective remote control or indoor control PCB (defective communication circuit)?
• Poor connection of wire between indoor-outdoor units during operation
(disconnection, loose connection)
• Anomalous communication between indoor-outdoor units by noise, etc.
• CPU-runaway on outdoor control PCB
*
• Occurrence of defective outdoor control PCB on the way of power supply (defective com-
munication circuit)?
• Defective outdoor control PCB on the way of power supply
• Blown fuse
• Defective indoor heat exchanger temperature thermistor (defective element, bro-
ken wire, short-circuit)
• Poor contact of temperature thermistor connector
*
• Defective indoor control PCB (Defective temperature thermistor input
circuit)?
• Defective indoor return air temperature thermistor (defective element, broken wire,
short-circuit)
• Poor contact of temperature thermistor connector
*
• Defective indoor control PCB (Defective temperature thermistor input
circuit)?
• Heating over-load (Anomalously high indoor heat exchanger temperature)
• Defective indoor heat exchanger temperature thermistor (short-circuit)
*
• Defective indoor control PCB (Defective temperature thermistor input circuit)?
• Defective drain pump (DM), broken drain pump wire, disconnected connector
• Anomalous float switch operation (malfunction)
*
• Defective indoor control PCB (Defective float switch input circuit)
*
• Defective indoor control PCB (Defective DM drive output circuit)?
• Defective optional parts (At optional anomalous input setting)
• When multi-unit control by remote control is performed, the number of units
is over
• Defective fan motor
• Indoor fan motor rotation speed anomaly
• Broken wire of remote control temperature thermistor
273
- -
'12 • PAC-T-178
Reference
Repair method
page
— —
Repair 298
Repair
299
Replacement of
remote control
Repair 300-304
Repair
306
Replacement of
remote control or
PCB
Repair
Power reset or
Repair
307
Replacement of
PCB
Replacement
Replacement, repair
of temperature
thermistor
308
Replacement of
PCB
Replacement, repair
of temperature
thermistor
309
Replacement of
PCB
Repair
Replacement of
temperature therm- 310
istor
Replacement of
PCB
Replacement, repair
of DM
Repair
311
Replacement of
PCB
Repair
Repair 312
Replacement, repair
313
Replacement
Repair 314
Replacement, repair
315
Replacement
Repair 316