On an LG Multi V 5 outdoor unit, CH26 is an "Outdoor unit inverter compressor operation error" (the inverter compressor failed to start) and CH29 is an "Outdoor unit inverter compressor overcurrent error" (the manual's detail line reads "Inverter compressor input current is >30A"). Per the LG MULTI V 5 Outdoor Unit Service Manual (Error No. 26, pp.151-152; Error No. 29, pp.153-154), either code can come from the refrigerant side, the compressor or the inverter PCB. Rule out overload conditions, wiring and, for CH29, supply voltage before you condemn either part; on units with two same-capacity inverters, the CH26 swap test shows whether the fault follows the compressor or the board.
CH26 vs CH29: what each code means
| Item | CH26 | CH29 |
|---|---|---|
| Codes by unit | 261 master, 262 slave 1, 263 slave 2 | 291 master, 292 slave 1, 293 slave 2 |
| Description | Outdoor unit inverter compressor operation error | Outdoor unit inverter compressor overcurrent error |
| Details | Inverter compressor start failure | Inverter compressor input current is >30A |
| Cause 1 | Overload error: piping is clogged, indoor or outdoor unit is blocked, EEV is blocked, or there is an overcharge in refrigerant | Overload operation: piping is clogged, indoor or outdoor unit is blocked, EEV is defective, refrigerant is overcharged |
| Cause 2 | Compressor insulation and/or motor has been damaged | Compressor insulation and/or motor is/are damaged |
| Cause 3 | Compressor wiring error | Input voltage is low |
| Cause 4 | Outdoor unit inverter PCB has been damaged (CT) | Outdoor unit inverter PCB assembly is damaged |
| Source | Multi V 5 service manual, pp.151-152 | Multi V 5 service manual, pp.153-154 |
Both lists put the system first and the parts last. A compressor that cannot start against a clogged line or an overcharge, or that draws too much current under that load, gives the same code as a failed compressor or a failed board.
Rule out the system before the parts
Both flowcharts open with "Is the installation correct?" and the same four checks:
- Check if piping is clogged or has been damaged.
- Check if outdoor or indoor units are blocked.
- Check the EEV. For CH26 the manual says to check that it is operating normally and that the connections are correct; for CH29, to check the EEV connector assembly and verify it is operating normally.
- Check the refrigerant pressure.
Only after the installation passes do the flowcharts move to the compressor and the board.
Bad compressor? The winding and wiring checks
Both codes use the same compressor checks:
- Check the resistance between each compressor terminal (U-V, V-W, W-U).
- Check the insulation resistance between the compressor terminal and the pipe.
- Check the inverter compressor PCB assembly U, V, W connections, check whether the wires have disconnected or been damaged, and check the compressor terminal connections for bad contacts.
The charts on these pages are drawn for the JQC068MA, JQC068MB / JQC068MBA, JQC048MA and JQC048MB / JQC048MBA compressors at 77°F and 167°F. Take the reference values from the chart for your compressor. As our practical advice: a winding that reads open, a phase pair that reads very differently from the other two, or a terminal with a measurable path to the pipe points at the compressor, not the board.
The CH26 flowchart also asks "Are the power wiring connections correct?" and says to check the R(L1), S(L2) and T(L3) wiring connections.
CH29 only: check the supply voltage
Low input voltage is a listed CH29 cause, and the flowchart asks "Is the input voltage normal?" The manual's check:
| Unit voltage | Abnormal if R~S, S~T or T~R phase voltage is | Source |
|---|---|---|
| 208-230V units | <180 V or >253 V | Multi V 5 service manual, Error No. 29 |
| 460V units | <414 V or >528 V | Multi V 5 service manual, Error No. 29 |
Measure all three phase pairs. If the supply is outside these limits, fix the supply or the power wiring first. That is our practical advice, and the manual's flowchart sends you back to checking power, wiring and installation rather than to a part.
Bad inverter board? The CH26 board checks
After the compressor and wiring, both flowcharts say to check the inverter compressor PCB assembly and the IPM. For CH26, Table 80 gives the values:
| Check | Checkpoint | Normal | Abnormal |
|---|---|---|---|
| Inverter PCB damage | Inverter PCB appearance, power off | Appearance good | Damage |
| 5 V and 15 V lines | Measure 5 V and 15 V line resistance | No value given in the table | - |
| IGBT module | P to U, V, W and N to U, V, W | 0.38 V to 0.7 V | Non-normal |
| Inverter drive circuit (diode) | Diode | 0.38 V to 0.7 V | Non-normal |
The CH29 pages carry the same instruction to check the inverter compressor PCB assembly and IPM but print no checkpoint table. They do repeat the note: "Always apply heat transfer paste to the new inverter PCB heat sink before installing."
The swap test on two-compressor units (CH26)
For units with two inverters of the same capacity, Figure 73 ("Two Compressor Additional Check Procedure, Same Capacity Inverter Only") shows the standard connection with Inverter 1 showing CH26, then the compressor connections crossed between the inverters. The manual's conclusions:
- "If Inverter 2 has CH26 displayed, then Comp. 1 is defective."
- "If Inverter 1 consistently displays CH26, then Inverter 1 is defective."
So if the code follows the compressor, replace the compressor; if it stays with the inverter, the board is the suspect. The pages we cite print this figure for CH26 only; the CH29 pages do not include it.
Parts involved
| Component | Role in this issue | Where to find it |
|---|---|---|
| Inverter compressor (068) | Damaged compressor insulation or motor is a listed cause of both codes. The manual's charts include JQC068MB / JQC068MBA. | LG TBZ37416201 Compressor, JQC068MBA Inverter Scroll – Multi V 5 208/230V |
| Inverter compressor (048) | The manual's charts include JQC048MB / JQC048MBA. | LG TBZ37416101 Compressor, JQC048MBA – Multi V 5 outdoor unit |
| Inverter PCB | A damaged inverter PCB is the last listed cause of both codes. Inverter boards differ by model and voltage. | LG EBR88279008 Inverter PCB Assembly – Multi V 5 outdoor unit |
| Heat transfer paste | The manual calls for paste on a new inverter PCB heat sink. | LG RAC34537401 Heat Transfer Paste for Inverter PCB & Heat Sink Service |
| EEV and other parts | A blocked or defective EEV is part of the overload cause. EEVs and coils are model-specific. | LG Parts |
Scope: This article covers Error No. 26 (CH26; 261 to 263) and Error No. 29 (CH29; 291 to 293) as written in the LG MULTI V 5 Outdoor Unit Service Manual, pp.151-154, including Table 80 and Figure 73. Other Multi V generations may define or test these codes differently. The parts above are examples listed by live product title, not a fit confirmation for your unit.
Before you order
Read the outdoor unit's model and serial number from the nameplate and the compressor model from the compressor label. For where LG prints its Multi V code tables, see where to find the LG Multi V error code table. For the inverter board IPM fault, see LG CH21 IPM fault: what to check before buying an inverter board. If your compressor number has been superseded, see HVAC part number supersessions. To confirm fit, contact us at help@totalhvacparts.com or 302-219-4994 with the model, serial number, error code and your readings.
Frequently Asked Questions
What does CH26 mean on an LG Multi V?
The LG Multi V 5 outdoor unit service manual defines Error No. 26 as "Outdoor unit inverter compressor operation error," with the detail "Inverter compressor start failure." Causes include overload, damaged compressor insulation or motor, a compressor wiring error and a damaged inverter PCB.
What does CH29 mean on an LG Multi V?
Error No. 29 is "Outdoor unit inverter compressor overcurrent error." The manual's detail line reads "Inverter compressor input current is >30A," and the causes include overload operation, a damaged compressor, low input voltage and a damaged inverter PCB assembly.
How do I know if it's the compressor or the inverter board on an LG Multi V?
Check the installation, then the compressor terminal resistance, insulation to pipe and U, V, W wiring. On two-compressor units with same-capacity inverters, the CH26 swap test applies: if the code moves to the other inverter, the compressor is defective; if it stays, the inverter is.
What supply voltage should I check on a CH29 on an LG Multi V?
The manual says to check whether any phase-to-phase voltage is below 180 V or above 253 V on 208-230V units, or below 414 V or above 528 V on 460V units.
Sources
- LG MULTI V 5 Outdoor Unit Service Manual, LG Electronics U.S.A., Error Codes section, Error No. 26 (pp.151-152; causes, flowchart, Table 80, Figure 73) and Error No. 29 (pp.153-154; causes, flowchart, phase voltage limits), cited by name and page; not linked
- Live product titles for the parts listed above, as shown on each product page
LG Multi V outdoor units involve line voltage, stored charge in inverter board capacitors, pressurized refrigerant and rotating equipment. Service should be performed only by qualified personnel, following LG's service manual for your unit and your facility's lockout/tagout procedures.