Diagnosing Of Microcomputer Circuit; Selfdiagnosis Function - Mitsubishi Heavy Industries FDTC40ZHXV Technical Manual

1.6.3 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 side
Remote controller Indoor unit control PCB Outdoor unit control PCB
Error code Red LED Red LED
Stays OFF
No-indication Stays OFF Stays OFF Stays OFF
*
3 times
flash
or stays
Stays OFF
OFF
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
3 times
flash
Stays OFF
1 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.
Location of
Green Green
trouble
Red LED
LED (1) LED (1)
Keeps Keeps
Stays OFF —
flashing flashing
2 times Indoor unit power
Stays OFF
flash supply
Remote controller
wires
Keeps Keeps
Stays OFF
flashing flashing
Remote controller • Defective remote controller PCB
Indoor-outdoor
units connection
Keeps 2 times Keeps
wire
flashing flash flashing
Remote controller • Improper setting of master and slave by remote controller
Remote controller
*
wires (Noise)
Keeps Keeps
Stays OFF
flashing flashing
Remote controller
indoor unit control
PCB
Indoor-outdoor
Keeps 2 times Keeps
units connection
flashing flash flashing
wire
(Noise)
Keeps Keeps
Stays OFF
flashing flashing
Outdoor unit control
PCB
Outdoor unit control
Keeps
PCB
Stays OFF Stays OFF
flashing
Fuse
Indoor unit heat
exchanger tempera-
Keeps Keeps
ture thermistor
Stays OFF
flashing flashing
Indoor unit PCB
Indoor unit return
air temperature
Keeps Keeps
thermistor
Stays OFF
flashing flashing
Indoor unit control
PCB
Installation or oper-
ating condition
Indoor unit heat
Keeps Keeps
Stays OFF exchanger tempera-
flashing flashing
ture thermistor
Indoor unit control
PCB
Drain trouble
Float switch
Keeps Keeps
Stays OFF
flashing flashing
Indoor unit control
PCB
Option
Keeps Keeps Number of con-
Stays OFF
flashing flashing nected indoor units
Indoor unit No. set-
ting
Keeps Keeps
Stays OFF
flashing flashing
Remote controller
wires
Fan motor
Keeps Keeps
Stays OFF
Indoor unit control
flashing flashing
PCB
Keeps Keeps Indoor unit control
Stays OFF
flashing flashing PCB
Remote controller
Keeps Keeps
Stays OFF temperature therm-
flashing flashing
istor
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.
• Poor connection, breakage of indoor-outdoor units connection wire
• Poor connection of remote controller signal wire (White)
• Intrusion of noise in remote controller wire
*
• Defective remote controller or indoor unit 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 unit control PCB
*
• Occurrence of defective outdoor unit control PCB on the way of power supply (defective
communication circuit)?
• Defective outdoor unit control PCB on the way of power supply
• Blown fuse
• Defective indoor unit heat exchanger temperature thermistor (defective element,
broken wire, short-circuit)
• Poor contact of temperature thermistor connector
*
• Defective indoor unit control PCB (Defective temperature thermistor input
circuit)?
• Defective indoor unit return air temperature thermistor (defective element, broken
wire, short-circuit)
• Poor contact of temperature thermistor connector
*
• Defective indoor unit control PCB (Defective temperature thermistor input
circuit)?
• Heating over-load (Anomalously high indoor unit heat exchanger temperature)
• Defective indoor unit heat exchanger temperature thermistor (short-circuit)
*
• Defective indoor unit control PCB (Defective temperature thermistor input circuit)?
• Defective drain pump (DM), broken drain pump wire, disconnected connector
• Anomalous float switch operation (malfunction)
*
• Defective indoor unit control PCB (Defective float switch input circuit)
*
• Defective indoor unit 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
• No master is assigned to slaves.
• Anomalous remote controller wire connection, broken wire between master and slave units
• Defective fan motor (FDT)
• Defective indoor unit control PCB
• Improper operation mode setting
• Broken wire of remote controller temperature thermistor
247
– –
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 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
Replacement
Repair
Repair
Reference
page
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