Diagnosing Of Microcomputer Circuit; Check Lamp (Yellow) Flashing; Run Lamp (Green) Flashing; Table Of Inspection Items Based On Error Codes - Mitsubishi FDTN208HEN-S Instruction Manual

6.6.3 Diagnosing of microcomputer circuit

(1) Before starting diagnosis
(a) Required tools and measurement equipment
For unit disassembling
Small and large Philips screw driver, Flat head screw driver, Wrench
For diagnosis
Tester (A general tester will do)
(Diagnosis tools and equipment for refrigeration circuit should be prepared if necessary.)
(2) Selfdiagnosis function
(a) Indoor unit side
Only case of wireless remote control model.

Check Lamp (yellow) Flashing

If the heat exchanger thermistor temperature of indoor unit is
measured at -50°C or lower for 6 minutes or more following
1 time flash
operation of the compressor.
If the return thermistor temperature of indoor unit is measured
2 time flash
at -50°C or lower for 6 minutes or more after turning the power
ON.
Float switch operation
4 time flash
If the heat exchanger thermistor temperature of indoor unit is meas-
ured at 25°C or higher for 40 minutes or more following opera-
5 time flash
tion of the compressor.
If the indoor heat exchanger thermistor temperature is detected
twice to be 68°C or over within 60 minutes during the heating
6 time flash
operation.

Run Lamp (green) Flashing

6 time flash
During the low voltage protection control 52 C OFF (Conpressor,
Outdoor unit)
Note (1) Inspection LED display has a cycle of 8 seconds (flashing time of 0.5 seconds).
Only case of wired remote control model.

Table of inspection items based on error codes

Location of Problem
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
Insufficient refrigerant
E57
Indoor unit heat exchanger thermistor
Indoor unit circuit board
Flashing Conditions
Flashing Conditions
• 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)
• Gas leak.
• Indoor unit heat exchanger thermistor defective (short circuit). Indoor unit circuit board
defective (defective thermistor input circuit)?
Nature of Breakdown
Heat exchanger thermistor of in- Disconnection on heat ex-
door unit abnormality. changer thermistor, Poor con-
nection of connector.
Return thermistor of indoor unit Disconnection on return ther-
abnormality. mistor. Poor connection of con-
nector.
Drain abnormality. Drain reverse slope.
Drain pump abnormality.
Float switch abnormality.
Insufficient gas.
Abnormality caused by insuffi-
cient refrigerant.
Clogged air filter
Heating overload error
Shortcircuit on the indoor unit
Shortcircuit of heat exchanger
thermistor
Nature of Breakdown
When the power source voltage Restore automatically at 85% of
is 80% of rating or lower. rating or higher.
Cause
FDTN-H
Cause
Cause
273