Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 355

(c) Inspection method when there are fault lamps (display lamps on indoor unit).
(i) Only case of wireless remote control model
1
Defective indoor unit heat exchanger thermistor
Indoor unit
Check Lamp (yellow)
Is the indoor
unit heat exchanger
thermistor connector
connection OK?
NO
Correction
2
Defective return air thermistor
Indoor unit
Check Lamp (yellow)
Is the return air
thermistor connector
connection OK?
NO
Correction
3
Drain abnormality
Indoor unit
Check Lamp (yellow)
Is there any
overflow?
Is the float
switch tripper?
Defective indoor unit PCB
ment (Defective DM driving output cir-
cuit, defective float switch input cir-
cuit)
Defective indoor unit PCB
ment (Defective indoor unit heat
1 time flash
exchanger thermistor input circuit)
Are characteristics
YES
of indoor unit heat
exchanger thermistor OK
or is not there any
broken wire?
Defective indoor unit heat exchanger
thermistor
2 time flashes
Is the return air
YES
thermistor characteristics
OK or is there a
broken wire?
Defective return air
thermistor
4 time flashes
YES
NO
YES
Repair or replace the
float switch
NO
Replace-
Replace-
YES
NO
Replacement
Defective indoor unit PCB
YES
Replacement (Defective return air
thermistor input circuit)
NO
Note (1) Characteristics as per the above graph.
Replacement
Is the angle of
YES
drain piping good. Is there
any problem?
Repair
Note (1) Check if power source is there between DM connectors.
FDT ( N ) -H
Return air thermistor (Th A)
I-
Indoor unit heat exchanger thermistor
(Th R)
I-
Resistance temperature characteristics
15
10
5kΩ at 25˚C
5
0 10 20 30
Temperature (˚C)
Note (1) 22.5 kΩ at -6˚C
Defective indoor unit PCB Replace-
ment (Defective condensate motor output
circuit)
NO
(1)
Is there output
for condensate motor
(DM)?
YES
¡Check DM broken wire, burning, locking.
¡Are there any DM connector loose.
¡Are there any PCB faston terminal loose.
¡Are there any DM wire broken.
40 50
353