LG Multi V5 Service Manual page 145

Please refer to the Safety Precautions on pages 4-7 for more detail to prevent injury or death regarding the operation and service
WARNING
troubleshooting of the Multi V product.
Measuring the resistance between
each compressor terminal.
* Heat Sink
Table 78: Error No. 21 Checkpoint Details.
Cause
15V Voltage Measurement
Under Voltage (15V)
Check Inverter PCB appearance
Inverter PCB
IGBTM (Check IGBT)
Damaged
Figure 72: Two Compressor Additional Check Procedure (Same Capacity Inverter Only).
Standard Connection.
Example: Inverter 1, CH21
displayed.
Inv.1
Inv.2
- CH21
Comp.1 Comp.2
P and N Terminals.
Screws.
Check DC link connections.
Check
(Inverter connector)
Measure 5V,15V line 5V, 15V Resistance
P-U,V,W / N-U,V,W
Inverter Drive Circuit
(Check diode)
If Inverter 2 has CH21 displayed,
then Comp. 1 is defective.
Inv.1
Comp.1
Due to our policy of continuous product innovation, some specifications may change without notification.
©LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. "LG" is a registered trademark of LG Corp.
Compressor wiring
connections.
Checklist
Check Point Normal
Voltage 14.5V ~ 15.5V
Appearance Good
0.38V ~ 0.7V
Diode 0.38V ~ 0.7V
Cross Connections after Operation.
Inv.2
- CH21
Comp.2
ERROR CODES
Error No. 21, continued.
R
S
T
Images here are representative of system
components. Actual component appearance
depends on model and system type.
Defective
Abnormal
Parts
Inverter PCB
Damage
Inverter PCB
Non-normal
Non-normal
If Inverter 1 consistently displays
CH21, then Inverter 1 is defective.
Inv.1
- CH21
or
Comp.1
App.
A2 (Power ON)
B1 (Power Off)
Inv.2
Comp.2
145