Mitsubishi Heavy Industries SCM71ZM-S1 Technical Manual page 225

8.2 FDTC, FDEN, FDE and FDUM series
8.2.1 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 Stays OFF
*
3-time
flash
or
WAIT
Stays OFF
INSPECT I/U
Stays OFF
2-time
flash
2-time
flash
2-time
flash
1-time
flash
1-time
flash
Keeps
flashing
1-time
flash
1-time
flash
Stays OFF
Keeps
flashing
1-time
flash
1-time
flash
1-time
flash
Stays OFF
Note (1) Normal indicator lamp (Indoor unit: 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
main PCB
Location of trouble
Green
Red LED
LED (1)
Keeps
Stays OFF —
flashing
Indoor unit power source
Remote control wires
Keeps
Stays OFF
flashing
Remote control
Indoor-outdoor units connection
Keeps
wire
Stays OFF
flashing
Remote control
Remote control wires (Noise)
*
Keeps
Stays OFF
flashing
Remote control indoor control
PCB
Keeps 6-time Indoor-outdoor units connection
flashing flash wire
(Noise)
Keeps 6-time
flashing flash
Outdoor control PCB
Outdoor control PCB
Keeps 6-time
flashing flash
Fuse
Indoor heat exchanger tempera-
ture thermistor
Keeps
Stays OFF
flashing
Indoor control PCB
Indoor return air temperature
thermistor
Keeps
Stays OFF
flashing
Indoor control PCB
Installation or operating condi-
tion
Keeps Indoor heat exchanger tempera-
Stays OFF
flashing ture thermistor
Indoor control PCB
Drain trouble
Float switch
Keeps
Stays OFF
flashing
Indoor control PCB
Option
Keeps Number of connected indoor
Stays OFF
flashing units
Keeps Address
Stays OFF
flashing setting error
Fan motor
Keeps
Stays OFF
flashing
Indoor control PCB
Keeps
Stays OFF Indoor control PCB
flashing
Fan motor
Keeps
Stays OFF
flashing
Indoor power PCB
Keeps Remote control temperature
Stays OFF
flashing 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)
• 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 source (defective communication
circuit)?
• Defective outdoor control PCB on the way of power source
• Blown fuse
• Defective indoor heat exchanger temperature thermistor (defective element, broken 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 option parts (At optional anomalous input setting)
• When multi-unit control by remote control is performed, the number of units is over
• Address setting error of indoor units
• Defective fan motor
• Defective indoor control PCB
• Improper operation mode setting
• Indoor fan motor rotation speed anomaly
• Defective indoor power PCB
• Broken wire of remote control temperature thermistor
224
- -
'17 • SCM-T-225
Repair method
Replacement of
remote control
* For wire breaking at power ON, the LED is OFF
Replacement of
remote control or
Power reset or
Replacement of
Replacement
Replacement,
repair of tempera-
ture thermistor
Replacement of
Replacement,
repair of tempera-
ture thermistor
Replacement of
Replacement
of temperature
thermistor
Replacement of
Replacement,
repair of DM
(In case of FDTC, FDUM)
Replacement of
Replacement,
(In case of FDTC, FDUM)
Replacement
Replacement, repair
(In case of FDTC, FDUM)
Replacement
Reference
page
— —
Repair 247
Repair
248
Repair 249−253
Repair
254
PCB
Repair
Repair
255
PCB
256
PCB
257
PCB
Repair
258
PCB
Repair
259
PCB
Repair
Repair 260
Repair 261
repair
262
Repair 263
264
Repair 265