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AA
Check of outdoor unit
Compressor and/or outdoor fan motor doesn’t operate.
Yes
Compressor
doesn't operate.
Yes
Yes
Is there 230V AC between 3 on the
compressor contactor (52C) and N
on the outdoor terminal block (TB1)?
Operate the unit in COOL or HEAT mode by pressing the EMERGENCY OPERATION switch.
3-minute time delay works.
Test run operation operates for 30 minutes.
Outdoor fan motor
doesn't operate.
No
Rectify the indoor and
outdoor connecting wire.
Rectify the connecting wire.
Check the compressor and compressor
capacitor, and rectify the connecting wire.
Start
Yes
Is there 230V AC between 4 on the
compressor contactor (52C) and
TAB20 on the deicer P.C. board?
Is there 230V AC between L–N
on the outdoor terminal block (TB1)?
Replace the
deicer P.C. board.
Replace the
deicer P.C.
board.
No
No
Yes
Yes
No
Check the outdoor fan motor
and rectify the connecting
wire.
Is there 230V AC between 4 on the
compressor contactor (52C) and
TAB 20 on the deicer P.C. board?
Replace the
deicer P.C. board.
No
Yes
Rectify the indoor and
outdoor connecting wire.
Rectify the connecting wire.
Is there 230V AC between L–N on
the outdoor terminal block (TB1)?
No
No
Is the switch SW2-2 on the
indoor electronic control
P.C. board set to MUH type?
No
Change the switch SW-2-2
on the indoor electronic control
P.C. board to MUH type.
Yes
+
–
Is there 5V DC between J205 –J101 on
the deicer P.C. board?
+
–
Is there 5V DC between J205 –J101 on
the deicer P.C. board?
Compressor
(MC)
INNER
PROTECTOR
MUH-GA20/GA25VB
150i 5°C OPEN
90i10°C CLOSE
MUH-GA35VB
155i 5°C OPEN
90i10°C CLOSE
Part name
Check method and criterion
Measure the resistance between the terminals with a tester.
(Coil wiring temperature –10°C ~ 40°C)
Measure the resistance between the terminals with a tester.
(Coil wiring temperature –10°C ~ 40°C)
Figure
P
R
C
S
RED
BLK
WHT
MAINAUX.
WHTRED
BLK
MAIN
AUX.
FUSE
MUH-GA20VB - MUH-GA25VB - MUH-GA35VB -
E1E1E1
Defrost
thermistor
(RT63)
Measure the resistance with a tester.
(Part temperature –10°C ~ 40°C)
5kΩ ~ 60kΩ
Normal
Abnormal
Open or short-circuit
Normal
MUH-GA20VB
3.41~4.18Ω
5.41~6.63Ω
2.99~3.67Ω
2.46~3.01Ω
2.96~3.63Ω
C-R
C-S
Abnormal
Open or short-circuit
4.02~4.92Ω
MUH-GA25VB
MUH-GA35VB
Normal
MUH-GA20VB
323 ~ 396 Ω
241 ~ 296 Ω
189 ~ 233 Ω
270 ~ 332 Ω
WHT-BLK
BLK-RED
Abnormal
Open or short-circuit
MUH-GA25/GA35VB
P INNER PROTECTOR
Color of
lead wire
10-3. Trouble criterion of main parts
Outdoor fan
motor
(MF)
INNER FUSE
145i 2°C
CUT OFF
10-4. Troubleshooting flow
OB387-1.qxp 05.2.21 10:03 AM Page 24