Mitsubishi Heavy Industries FDT71VNXVD Service Manual page 26

2. MAINTENANCE DATA
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 controller 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 controller Indoor control PCB
Green
Error code Red LED Red LED
LED (1)
Keeps
Stays OFF
flashing
Stays OFF Stays OFF
No-indication Stays OFF
*
Keeps
3 times
flashing
flash
WAIT
or Keeps
Stays OFF
INSPECT I/U flashing
Keeps
Stays OFF
flashing
2 times Keeps
flash flashing
2 times Keeps
flash flashing
2 times Keeps
flash flashing
Keeps
1 time flash
flashing
Keeps
1 time flash
flashing
Keeps
flashing
Keeps
1 time flash
flashing
Keeps
1 time flash
flashing
Keeps
Stays OFF
flashing
3 times Keeps
flash flashing
Keeps
Stays OFF
flashing
Keeps
1 time flash
flashing
Keeps
Stays OFF
flashing
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
trouble
Red LED
LED (1)
Keeps
Stays OFF — • Normal operation
flashing
2 times Indoor unit power
Stays OFF • Power OFF, broken wire/blown fuse, broken transformer wire
flash supply
Remote controller • Poor connection, breakage of remote controller wire * For wire breaking at power ON, the
wires
Keeps
Stays OFF
flashing
Remote controller • Defective remote controller PCB
Indoor-outdoor
units connection • Poor connection, breakage of indoor-outdoor units connection wire
2 times Keeps
wire
flash flashing
Remote controller • Improper setting of master and slave by remote controller
• Poor connection of remote controller signal wire (White)
Remote controller
*
wires (Noise)
• Intrusion of noise in remote controller wire
Keeps
Stays OFF
flashing
Remote controller
*
indoor control PCB
Indoor-outdoor • Poor connection of wire between indoor-outdoor units during operation
2 times Keeps
units connection
flash flashing
wire • Anomalous communication between indoor-outdoor units by noise, etc.
(Noise) • CPU-runaway on outdoor control PCB
Keeps
Stays OFF
flashing
Outdoor control *
PCB
Outdoor control
• Defective outdoor control PCB on the way of power supply
PCB
Stays OFF Stays OFF
Fuse • Blown fuse
Indoor heat • Defective indoor heat exchanger temperature thermistor (defective element, bro-
exchanger tempera-
Keeps
ture thermistor • Poor contact of temperature thermistor connector
Stays OFF
flashing
*
Indoor control PCB
• Defective indoor return air temperature thermistor (defective element, broken wire,
Indoor return air
temperature therm-
Keeps
istor • Poor contact of temperature thermistor connector
Stays OFF
flashing
*
Indoor control PCB
Installation or oper-
• Heating over-load (Anomalously high indoor heat exchanger temperature)
ating condition
Indoor heat
Keeps
Stays OFF exchanger tempera- • Defective indoor heat exchanger temperature thermistor (short-circuit)
flashing
ture thermistor
*
Indoor control PCB
Drain trouble • Defective drain pump (DM), broken drain pump wire, disconnected connector
Float switch • Anomalous float switch operation (malfunction)
Keeps
Stays OFF
flashing *
Indoor control PCB
*
Option • Defective optional parts (At optional anomalous input setting)
Keeps Number of con- • When multi-unit control by remote controller is performed, the number of
Stays OFF
flashing nected indoor units
Indoor unit No. set-
•No master is assigned to slaves.
Keeps
ting
Stays OFF
flashing
Rcmote controller wires •Anomalous remote controller wire connection, broken wire between master and slave units
Fan motor • Defective fan motor
Keeps
Stays OFF
flashing
Indoor control PCB • Defective indoor control PCB
Keeps
Stays OFF Indoor control PCB • Improper operation mode setting
flashing
Remote controller
Keeps
Stays OFF temperature therm- • Broken wire of remote controller temperature thermistor
flashing
istor
-
Description of trouble
LED is OFF.
* For wire breaking at power ON, the LED is OFF
• Defective remote controller or indoor control PCB (defective communication circuit)?
(disconnection, loose connection)
• Occurrence of defective outdoor control PCB on the way of power supply (defective com-
munication circuit)?
ken wire, short-circuit)
• Defective indoor control PCB (Defective temperature thermistor input
circuit)?
short-circuit)
• Defective indoor control PCB (Defective temperature thermistor input
circuit)?
• Defective indoor control PCB (Defective temperature thermistor input circuit)?
• Defective indoor control PCB (Defective float switch input circuit)
• Defective indoor control PCB (Defective DM drive output circuit)?
units is over
-
26
'10 • PAC-SM-137A
Repair method
—
Repair
Repair
Replacement of
remote controller
Repair
Repair
Replacement of
remote controller or
PCB
Repair
Power reset or
Repair
Replacement of
PCB
Replacement
Replacement, repair
of temperature
thermistor
Replacement of
PCB
Replacement, repair
of temperature
thermistor
Replacement of
PCB
Repair
Replacement of
temperature therm-
istor
Replacement of
PCB
Replacement, repair
of DM
Repair
Replacement of
PCB
Repair
Repair
Repair
Replacement, repair
(In case of FDTC, FDT, SRK)
Replacement
Repair
Repair
Reference
page
—
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