124 125
_TROUBLE SHOOTING GUIDE BOOK _
- 140 -
Copyright ©2017 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
1. Overload operation
2. Fan Motor defect
3. Fan PCB assembly defect
4. Fan Motor connector insert defect
5. Condenser icing or blocking
Error No. Error Type Error Point Main Reasons
Output current is over 7A.
Fan Over Current Error
77*
Master 771
Slave1 772
Slave2 773
Slave3 774
n Error Diagnosis and Countermeasure Flow Chart
No
Is installation
condition normal?
Is motor wire connection
condition normal?
1.Check if color of motor output terminal(U,V,W) connector matched with PCB’s
2.Check wire disconnection and wiring
→
Reassemble or replace if abnormality found
Is Fan PCB assembly normal?
Yes
No
Recheck power and
installation condition
Yes
No
1. Check resistance between each motor output terminal
2. Check insulation resistance between ODU fan motor terminal(U,V,W) and pipe (over 100M )
→
Replace fan motor if abnormality found
No
Are the resistance
Between each phase and insulation
resistance of motor output
terminal normal?
Yes
Check ODU fan motor assemble condition and locking
→
Reassemble or replace if abnormality found
Measuring fan motor phase
resistance
1. Check fan PCB assembly IPM normal
→
Replace Fan PCB assembly
Chassis UXA UXB
Resistance 15 ± 7 % Ω 13 ± 7 % Ω
Error No. Error Type Error Point Main Reasons
77*
Fan Over Current
Error
Output current is
over 7A.
1. Overload operation
2. Fan Motor defect
3. Fan PCB assembly defect
4. Fan Motor connector insert defect
5. Condenser icing or blocking
- 139 -
Copyright ©2017 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
n
Error diagnosis and countermeasure flow chart
Error No. Error Type Error Point Main Reasons
75*
Master
Slave1
Slave2
Slave3
Fan CT Sensor Error
Offset of Micom which
which sense the fan
motor phase current is
not 2.5V ± 0.3V
1. Input Voltage is abnormal (not 15V)
2. Fan PCB assembly defect
3. Power wire open and connecting fault
4. Inverter PCB assembly defect
Is input voltage normal?
No
1. Check 15V input power wiring conditions
Rewire them if abnormality found
1. Replace Fan PCB
No
Is Fan PCB normal?
Yes
1. Check Fan PCB IPM normal or not.
Replace Fan PCB
No
Is there any error
When power reset?
Yes
Yes
Recheck Power and
Installation Condition
Check DC input power 15V on Inverter PCB.
Error No. Error Type Error Point Main Reasons
75*
Fan CT Sensor
Error
Offset of Micom
which which sense
the fan motor phase
current is not 2.5V
± 0.3V
1. Input Voltage is abnormal (not 15V)
2. Fan PCB assembly defect
3. Power wire open and connecting fault
4. Inverter PCB assembly defect
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