Mitsubishi Electric MSC-GA25VB-E1 Service Manual page 14

9-4. Trouble criterion of main parts
MSC-GA20VB -
E1
MSC-GA25VB -
E1
MSC-GA35VB -
E1
Part name
Room
Measure the resistance with a tester.
temperature
(Part temperature 10°C ~ 30°C)
thermistor (RT11)
Indoor coil
thermistor (RT12)
Measure the resistance between the terminals with a tester.
(Coil wiring temperature10°C ~ 30°C)
Indoor fan
motor (MF)
INNER FUSE
136i3°C Measure the voltage Power ON.
CUT OFF
Measure the resistance between the terminals with a tester.
(Part temperature10°C ~ 30°C)
Vane motor
(MV)
9-5. Troubleshooting flow
When OPERATION INDICATOR lamp flashes 3-time.
Indoor fan motor doesn't operate.
A A Check of indoor fan motor
No
Reconnect the lead wires.
Disconnect lead wires from connector CN211 on indoor electronic control P.C. board.
Measure resistance between lead wires No.1 and No.5 and then No.3 and No.5.
Is resistance 0 (short circuit) or ∞ (open circuit)?
Check method and criterion
Normal
MSC-GA20/GA25/GA35VB
8kΩ ~ 20kΩ
Color of
lead wire
MSC-GA20/GA25VB
WHT-BLK 271 ~ 295Ω
BLK-RED 180 ~ 196Ω
Color of
lead wire
MSC-GA20/GA25/GA35VB
BRN-YLW
(When fan revolved one time)
YLW-GRY
Normal
MSC-GA20/GA25/GA35VB
240 ~ 260Ω
Turn OFF the power supply.
Check connector CN211 visually.
Are lead wires connected?
Yes
Yes ( 0 or ∞ )
Repair or replace the indoor fan motor.
Normal
MSC-GA35VB
215 ~ 233Ω
305 ~ 331Ω
Normal
4.5 ~ 5.5V
Remain 0V or 5V
0V 5V 0V
(Approx.)
Abnormal
Open or
short-circuit
Yes
Is soldered point of the
connector correctly soldered?
Turn ON the power supply. Stop it if the unit operates.
Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure volt-
No
age No.2(+) and No.3(-) on CN121.
(others)
No
Replace the indoor electronic control P.C. board.
14
Abnormal
Open or
short-circuit
Abnormal
Open or
short-circuit
Abnormal
No
Does voltage repeat 0V DC and 5V DC?
Yes
Figure
WHT
RED
BLK
FUSE
YLW
GRY
BRN
RED
ROTOR
YLW
BRN
GRN
ORN
Resolder it.