Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 173

Serial signal transmission abnormality
Are receiving lamps (LEDs 3 to 5) on?
YES
Outdoor printed circuit board defect.
Note: Please see page 174 for the inspection proce-
dure for the serial signal transmission abnor-
mality in the outdoor power supply.
High pressure abnormality
Notes (1) Cooling: Outdoor side, outdoor fan motor
Heating: Indoor side, indoor fan motor.
(2) Also check for air filter and heat-
exchange fin clogging.
Indoor fan motor error
Is connector connection good?
Is voltage applied to fan motor?
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.
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 the refrigerant charge correct?
Is there a short circuit?
Is the fan motor operating properly?
Inverter defective.
YES
NO
(Between White - Red)
YES
Defective fan motor
NO
Is the float switch operating?
NO
NO
Indoor printed circuit board is defective.
[Indoor/outdoor printed circuit board defect
Outdoor power source abnormality]
NO
YES
NO
YES
YES
(1)
YES
(1)
YES
NO
Correct connector
connection.
Defective indoor unit
PCB
YES
Inspect float switch.
Repair and clean.
SCM-HG (4 room)
The indoor printed circuit board is defective.
The power supply and signal wire are defective.
[Overcharge
Short circuit]
NO
Release refrigerant.
NO
Check the installation conditions.
NO
Inspect the fan motor.
[Defective fan motor,
defective PCB]
[Drain piping defective,
pump defect]
NO
Indoor printed circuit board
is defective.
Note (1) Drain pump is an option.
171