Mitsubishi SCM80ZA Manual page 61

Serial signal transmission abnormality
Are receiving lamps (LEDs 1 to 4) on?
YES
Outdoor printed circuit board defect.
Note(1) Please see page 61 for the inspection proce-
dure for the serial signal transmission abnor-
mality in the outdoor power supply.
Indoor fan motor error
Drain abnormality
Has an overflow developed?
YES
Is the drain piping clogged or at the
wrong gradient?
YES
Is there output for drain motor driver?
YES
Drain motor is defective. Inspect
wiring.
(4) Phenomenon observed after shortcircuit, wire breakage on thermistors, etc.
(a) Indoor unit
Operation
Thermistor
mode
Cooling
Room temperature
thermistor
Heating
Cooling
Heat exchanger
thermistor
Heating
(b) Outdoor unit
Operation
Thermistor
mode
Cooling
Heat exchanger
pipe thermistor
Heating
Cooling
Outdoor temperature
thermistor
Heating
Discharge pipe
All modes
thermistor
Does the voltage between 2 and 3
NO
on the indoor side oscillate between
(Flashing)
0 and 12V?
Does the voltage between 2 and 3
on the outdoor side oscillate
between 0 and 12V?
The outdoor printed circuit board is defective.
Is connector connection good?
YES
Is voltage applied to fan motor?
(Between White - Red)
YES
Defective fan motor
NO
Is the float switch operating?
NO
NO
Indoor printed circuit board is defective.
Shortcircuit
Release of continuous compressor operation command
Continuous compressor operation command is not released.
System can be operated normally.
High pressure control mode (Inverter stop command)
Shortcircuit
Defrosting is not performed.
Defrosting is not operated.
Compressor overload protection is disabled.
(Can be operated.)
[Indoor/outdoor printed circuit board defect
Outdoor power source abnormality]
NO
YES
NO
YES
NO
Correct connector
connection.
NO
Defective indoor unit
PCB
YES
Inspect float switch.
Repair and clean.
Phenomenon
Continuous compressor operation command is not released.
Release of continuous compressor operation command
Continuous compressor operation command is not released.
(Anti-frosting)
Hot keep (Indoor fan stop)
Phenomenon
System can be operated normally.
Defrosting is performed for 10 minutes at approx. 30 minutes.
System can be operated normally.
Defrosting is performed for 10 minutes at intervals of approx. 30 minutes.
Compressor stop (There is no inverter output.)
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The indoor printed circuit board is defective.
The power supply and signal wire are defective.
[Defective fan motor,
defective PCB]
[Drain piping defective,
pump defect]
NO
Indoor printed circuit board
is defective.
Note (1) Drain pump is an option.
Broken wire
Broken wire
111