Mitsubishi Heavy Industries SCM71ZM-S1 Technical Manual page 219

Rotor lock (SCM71, 80 only)
Drain abnormality (SRR only)
Is the drain piping clogged or at
the wrong gradient?
Is there output for drain motor driver?
Service valve (gas side) closed operation
(8) Phenomenon observed after shortcircuit, wire breakage on sensor
(a) Indoor unit
Operation
Sensor
mode
Cooling
Room temperature
sensor
Heating
Cooling
Heat exchanger
sensor
Heating
Cooling
Humidity sensor
(1)
Heating
Note (1) SRK35, 50ZJ, 50, 60ZJX, 71ZK-S,SRF25, 35, 50 only
■ Humidity sensor operation
Failure mode
①
②
①②
① ②
Has an overflow developed?
YES
YES
YES
Drain motor is defective.
Inspect wiring.
Shortcircuit
Are the service valve (gas side)
opened ?
YES
Is the checked result of power
transistor module OK ?
YES
Is the space for installation of indoor and/or
outdoor unit enough ?
Is there any short circuit of air on indoor
and/or outdoor unit ?
At heating, does the indoor fan motor run ?
Control input circuit resding
Is the filter clogged ?
Is there any liquid flooding ?
Is there any anomalous sound on the
compressor?
YES
After resetting power for several
times does it become normal ?
YES
Temporary noise may cause of anomaly.
If noise source can be found, take
countermeasure.
See page 215.
NO
Is the float switch operating?
YES
NO
Inspect float switch.
NO
Repair and clean.
Indoor PCB is defective.
Phenomenon
NO
Open the valve.
NO
Defective outdoor PCB
Air conditioning system operation
NO
Defective outdoor PCB
218
- -
'17 • SCM-T-225
Defective compressor, defective
outdoor PCB
main
[Drain piping defective,pump defect,
float switch, indoor PCB]
NO
Indoor PCB is
defective.
Service valve (gas side) closed,
Defective outdoor PCB
Disconnected wire
Replace.
Replace.