Fdtc Series - Mitsubishi Heavy Industries SRK20ZJX-S Service Manual

2.2 FDTC series

2.2.1 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
Error code Red LED Red LED
Stays OFF
No-indication Stays OFF
Stays OFF Stays OFF Stays OFF
*
3 times
flash
WAIT or
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
Stays OFF
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 supply
Remote controller wires
Keeps
Stays OFF
flashing
Remote controller
Indoor-outdoor units connection
Keeps
wire
Stays OFF
flashing
Remote controller
Remote controller wires (Noise)
*
Keeps
Stays OFF
flashing
Remote controller indoor con-
trol PCB
Keeps 6 times Indoor-outdoor units connection
flashing flash wire
(Noise)
Keeps 6 times
flashing flash
Outdoor control PCB
Outdoor control PCB
Keeps 6 times
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
Fan motor
Keeps
Stays OFF
flashing
Indoor control PCB
Keeps
Stays OFF Indoor control PCB
flashing
Keeps Remote controller temperature
Stays OFF
flashing thermistor
Description of trouble
• Normal operation
• Power OFF, broken wire/blown fuse, broken transformer wire
• Poor connection, breakage of remote controller wire * For wire breaking at power ON, the LED is OFF.
• Defective remote controller PCB
• Poor connection, breakage of indoor-outdoor units connection wire
• Improper setting of master and slave by remote controller
• Poor connection of remote controller signal wire (White)
• Intrusion of noise in remote controller wire
*
• Defective remote controller 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 communication
circuit)?
• Defective outdoor control PCB on the way of power supply
• 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 optional parts (At optional anomalous input setting)
• When multi-unit control by remote controller is performed, the number of units is over
• Defective fan motor
• Defective indoor control PCB
• Improper operation mode setting
• Broken wire of remote controller temperature thermistor
63
- -
'10 • SCM-SM-094
Repair method
—
Repair
Repair
Replacement of
remote controller
Repair
Repair
* For wire breaking at power ON, the LED is OFF
Replacement of
remote controller
or PCB
Repair
Power reset or
Repair
Replacement of
PCB
Replacement
Replacement,
repair of temper-
ature thermistor
Replacement of
PCB
Replacement,
repair of temper-
ature thermistor
Replacement of
PCB
Repair
Replacement
of temperature
thermistor
Replacement of
PCB
Replacement,
repair of DM
Repair
Replacement of
PCB
Repair
Repair
Replacement,
repair
Replacement
Repair
Repair
Reference
page
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