Diagnosing Of Microcomputer Circuit; Selfdiagnosis Function; Check Indicator Table; Table Of Inspection Items Based On Error Codes - Mitsubishi FDC 6 Series Service Manual

8.6.3 Diagnosing of microcomputer circuit

(1) Selfdiagnosis function

(a) Indoor unit side
(i) Only case of wireless remote control model.

Check indicator table

Failure mode on the indoor unit indicated by flashing Yellow LED and Green LED.
Indoor unit LED
Yellow Green
Indoor unit heat exchanger
1 time flash –
thermistor
Indoor unit circuit board
Indoor unit air return thermistor
2 time flashes –
Indoor unit circuit board
Failure in drainage
Float switch
4 time flashes –
Indoor circuit board
Insufficient refrigerant
5 time flashes –
Indoor unit heat exchanger thermistor
Indoor unit circuit board
Installation and operating conditions
6 time flashes – Indoor unit heat exchanger thermistor
Indoor unit circuit board
– 2 time flashes Low voltage protection
Note (1) Inspection LED display has a cycle of 8 seconds (flashing time of 0.5 seconds).
(ii) Only case of wired remote control model.

Table of inspection items based on error codes

Failure at:
Error Code
Operating switch wire
(signal noise)
E1
Circuit board for operating
switch or indoor unit
Indoor unit heat exchanger
thermistor
E6
Indoor unit circuit board
Indoor unit air inlet thermistor
E7
Indoor unit circuit board
Installation and operating conditions
E8 Indoor unit heat exchanger thermistor
Indoor unit circuit board
Failure in drainage
Float switch
E9
Indoor circuit board
E10
Number of indoor units connected
Insufficient refrigerant
E57 Indoor unit heat exchanger thermistor
Indoor unit circuit board
19
Failure at:
• Indoor unit heat exchanger thermistor defective (element defective or broken wire).
Defective connection of connector for thermistor.
• Indoor unit circuit board defective (defective thermistor input circuit)?
•
Indoor unit return thermistor defective (element defective or broken wire).
Defective connection of connector for thermistor.
Indoor unit circuit board defective (defective thermistor input circuit)?
•
• Failure with the condensate pump (DM), or open circuit or disconnection of connector with the condensate pump.
• Malfunctioning of the float switch (erroneous functioning)
Indoor unit circuit board defective (defective float switch input circuit)
•
• Indoor unit circuit board defective (defective DM driving output circuit)
Gas leak.
•
• Indoor unit heat exchanger thermistor defective (short circuit).
Indoor unit circuit board defective (defective thermistor input circuit)?
•
• Heating overload (temperature of heat exchanger for indoor unit abnormally high)
Indoor unit heat exchanger thermistor defective (short circuit)?
•
Indoor unit circuit board defective (defective thermistor input circuit)?
•
• When the power source voltage is 80% of rating or lower.
• Defective connection or broken wire for operating switch signal wire.
• Signal noise has entered the operating switch wire.
• Is the circuit board for the operating switch or the circuit board for the indoor unit is defective
(communication circuit defective)?
•
Indoor unit heat exchanger thermistor defective (element defective or broken wire). Defective
connection of connector for thermistor.
• Indoor unit circuit board defective (defective thermistor input circuit)?
•
Indoor unit return thermistor defective (element defective or broken wire). Defective connection
of connector for thermistor.
• Indoor unit circuit board defective (defective thermistor input circuit)?
• Heating overload (temperature of heat exchanger for indoor unit abnormally high)
• Indoor unit heat exchanger thermistor defective (short circuit).
• Indoor unit circuit board defective (defective thermistor input circuit)?
• Failure with the condensate pump (DM), or open circuit or disconnection of connector with the condensate pump.
• Malfunctioning of the float switch (erroneous functioning)
• Indoor unit circuit board defective (defective float switch input circuit)
• Indoor unit circuit board defective (defective DM driving output circuit)
• 1 Remote controller for multiple unit control, 17 or more indoor units connected
• Gas leak.
Indoor unit heat exchanger thermistor defective (short circuit).
•
Indoor unit circuit board defective (defective thermistor input circuit)?
•
Contents of the failure
Contents of the failure