Multi F Four-Way Ceiling Cassette Service Manual

Part 5. Trouble Shooting
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Copyright ©2014 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
21
DC PEAK
(IPM Fault)
• Instant over current
• Over Rated current
• Poor insulation of IPM
• An instant over current in the U,V,W phase
- Comp lock
- The abnormal connection of U,V,W
• Over load condition
- Overcharging of refrigerant Pipe length.
Outdoor Fan is stop
• Poor insulation of compressor
Display
code
Title Cause of error Check point & Normal condition
Is installation
condition normal?
No
Yes
Yes
Recheck power and installation condition
1. Check Pipe clogging/distortion
2. Check Covering (Indoor/Outdoor Unit)
3. Check EEV connector assemble condition/normal
operation
4. Check refrigerant pressure
→ Reassemble or manage if abnormality found
1. Check resistance between each terminal of compressor
(0.438~0.628±7%)
2. Check insulation resistance between compressor
terminal and pipe (over 2MΩ)
→ Replace compressor if abnormality found
Are the resistance
Between each phase and
insulation resistance of Inverter
compressor normal?
No
Yes
1. Check inverter PCB assembly U,V,W connector
connection condition
2. Check wire disconnection and wiring
3. Check compressor terminal connection condition
(bad contact)
→ Reassemble if abnormality found
Is compressor
Wire connection
condition normal?
No
Yes
Check inverter PCB assembly IPM normality
→ Replace inverter PCB assembly
Is inverter PCB assembly normal?
No
■ Error Diagnosis and Countermeasure Flow Chart
■ Comp checking method
Comp
Copper
pipe
Model
Resistance(Ω)
Resistance(Ω) at 20°C
36k
54k
Terminal
V-W
Inverter Comp.
0.628(at 25˚C)
W-U
0.628(at 25˚C)
U-V
V-W
W-U
U-V
0.628(at 25˚C)
0.438(at 25˚C)
0.438(at 25˚C)
0.438(at 25˚C)
2MΩ
2MΩ
2MΩ
Inverter
comp.
V-GND
W-GND
U-GND
Terminal
2MΩ
2MΩ
2MΩ
Constant
comp.
V
U
W
Comp
► A4UW36GFA0/A8UW54GFA0
WARNING
Before checking PCB or each outdoor electric parts, wait for 3 minutes after the power is off. When measuring at standby state
of power supply, after checking the measurement mode of the meter, be careful of the short-circuits with other parts.