EBR78643405 LG Refrigerator Main Control Board, the 746 Platform Assembly Whose Number LG Retired Without an Argument
Part EBR78643405 is the LG main control board documented against the 746 cabinets, meaning the 23 cubic foot counter-depth French door sold as the LMXC23746 and the 29.9 cubic foot four door sold as the LMXS30746S. Two things about it matter before you spend anything. First, its replacement path is the one point of complete agreement in this part of LG's catalogue: every source still carrying the number records the same single change, out of the EBR series altogether and into LG's CSP service numbering as CSP30020854. Second, its documented coverage is lopsided. On the tall cabinet it is named against every production run published for the model. On the counter-depth cabinet it is named against the first run only, with later production documented against a different assembly. This guide is built around those two facts.
What Does a Failing EBR78643405 Look Like From the Kitchen?
An EBR78643405 becomes a candidate when a 746 cabinet warms in both compartments at once while the panel still lights and accepts settings, when the freezer rear wall glazes with ice because defrost never completes, when ice and dispensed water fail alongside a temperature complaint, and when the machine compartment stays silent on a proven live outlet.
Everything electrical on these cabinets reports to one assembly. It reads the sensors, decides when cooling is due, drives the compressor circuit and the fans, schedules defrost, and talks to the door panel. One arbitrator holding that many jobs fails distinctively: instead of a single clean casualty, several unrelated functions start slipping inside the same short window.
- Both sections warming together while the control panel behaves entirely normally
- An evaporator cover behind the freezer sheeted in ice until air stops moving through it
- Ice production and water delivery quitting during the same period as a cooling complaint
- A panel gone dark or frozen mid screen on a cabinet that is still holding temperature
- Settings that will not hold, or a cabinet that resets itself without being asked
- Silence from the machine compartment once the outlet has been proven live
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Why Does Searching EBR78643405 Return a Part Number That Looks Nothing Like It?
Because LG moved this assembly out of the EBR series entirely. Four independent catalogues record the same single change, from EBR78643405 to CSP30020854, and one states plainly that the manufacturer replaced the number you searched for with that part. Nothing there is contested, which is unusual in this group. Your label still reads EBR78643405, and that remains the number to match.
The video above shows where the applied label sits on an appliance control board and how to read it before packaging is opened. That step matters more than usual here, because the number printed on your board is no longer the number the trade sells. One catalogue calls the successor an official LG change. Another forwards the old number to a page carrying a different assembly name. A third lists the successor under its own reference and names the old number as what it replaces. They agree, which is worth saying out loud in a family where neighbouring numbers have catalogues pointing arrows at each other. Photograph your label and buy against what it shows.
Which Complaints Belong to the Board and Which Belong to What It Watches?
Count the unrelated systems misbehaving. One dead function surrounded by healthy ones describes the hardware that performs it. Several sliding together describes the assembly they all answer to. On a 746 cabinet that arithmetic does most of the diagnostic work before a meter comes out.
Treat every row below as a direction for testing rather than a verdict. These cabinets hand one board two food compartments, an ice system, a water path and a display, which is why complaints beginning in four different places keep arriving at the same conclusion more often than the evidence warrants.
| Symptom | What It May Indicate | Recommended Next Step | Board? |
|---|---|---|---|
| Both compartments warm, panel bright and taking settings | Cooling is being requested and not produced, or was never requested | Confirm both evaporator fans spin up, then measure each probe where it plugs in. Feed a working board nonsense and it makes nonsense decisions, which looks identical from outside to a dead one. | Common |
| Heavy ice on the freezer rear wall, airflow choked | Defrost is not completing, or its heating path has opened | Meter the heating element, its thermal cutout and the defrost probe before anything else. Scheduling is all the board contributes; the melting depends on three cheap parts staying alive. | Defrost parts first |
| Ice stops while water still dispenses and temperatures hold | The ice maker assembly, its fill valve or its own sensor | Verify the ice compartment is cold enough and the water line has not frozen shut. When one subsystem quits while everything around it works, the cause is almost always inside it. | Ice hardware |
| Panel dark or unresponsive, cabinet cooling correctly | The display assembly or the loom that flexes at the hinge | Trace the cable through the hinge looking for chafing at the flex point, then test the panel. Copper flexed several thousand times a year fails before the electronics it feeds. | Harness first |
| Cooling, defrost and ice all degrading inside a fortnight | A shared point of command rather than three coincidences | Simultaneous failure across systems sharing nothing but a controller points at the controller. Eliminate the probes and fans, then treat this assembly as the primary suspect. | Board-related |
Which Panel Readouts Describe This Assembly, and Which Describe Its Sensors?
Sort the readouts into two groups. Most name a component the board is only observing, being a fan, a thermistor, an ice part or a defrost attempt, and those close by replacing the component. A smaller group describes a conversation or a switching stage inside the assembly itself. Published meanings vary by LG series and revision, so confirm yours in your own documentation.
That division is the most useful thing to take into a code lookup. A refrigerator does not announce which part failed. It announces which circuit stopped answering as expected, and very often that circuit is something the board merely watches, which makes the job far cheaper. Where the report is about lost contact, wiring is at least as likely as electronics.
| Group | What It May Indicate | Is It This Board? |
|---|---|---|
| Anything naming a fan circuit | Airflow was requested and could not be verified. A frozen blade, a motor at the end of its bearings or a broken feed all report this way | Fan first |
| Anything naming a temperature sensor | A resistance value no working probe could produce. LG's published procedure for this vintage tests the connector, then the probe, and reaches electronics only if both survive | Sensor first |
| Anything naming defrost | A defrost period expired with the evaporator still frozen. Three parts carry that instruction to its conclusion, and any of them failing produces the identical report | Test the defrost circuit |
| Anything naming the ice section | A component inside the dedicated ice compartment has gone quiet. That compartment holds several small parts, each cheap and each a routine failure | Ice parts first |
| Anything describing a communication failure | Two electronic assemblies have stopped exchanging messages. On a door mounted panel the cable bending at the hinge is the weakest link by a wide margin | Harness before board |
| Anything about the compressor or refrigerant | Two very different jobs. A switching stage belongs to the board; a refrigerant problem belongs to a licensed technician with recovery equipment and cannot be fixed electronically | Separate the two |
| A blank display on a warm refrigerator | Nothing is reported because nothing believes anything is wrong. A cabinet that quietly stopped requesting cooling points harder at this assembly than any coded report does | Board-related |
What Has to Be Cleared Before an EBR78643405 Is Worth Buying?
Five checks decide it: does your label read EBR78643405 through to its last character, do the digits trailing your model code fall inside the documented runs, do the compartment thermistors measure sensibly, do the defrost heater and thermal fuse show continuity, and does every fan blade turn freely. The first two cost nothing but attention.
This check belongs at the front of the job on this board, because coverage is not even across the two cabinets it serves. Published records name it against the 29.9 cubic foot cabinet in both recorded runs, and against the 23 cubic foot counter-depth cabinet in the first run only. The counter-depth model page lists further runs beyond that, documented against a different assembly. A matching model code is therefore encouraging rather than conclusive until the trailing digits agree too.
Temperature probes are this assembly's only source of information. Corrupt that input and every decision downstream is corrupted with it, producing behaviour a homeowner reads as total electronic failure. LG's own diagnostic order puts electronics last for exactly this reason, and probes are among the cheapest parts in the cabinet.
Ice choking the freezer generates more service calls on this class of refrigerator than almost anything else, and the electronics are seldom responsible. Timing the cycle is the board's entire contribution. Clearing the frost requires a live heating element, an intact thermal cutout and a probe able to report when to stop. Break the chain anywhere and the outcome is identical.
Air moves through several separate paths on this platform, and any of them can be blocked mechanically while the electronics work perfectly. Usefully, each failure presents differently. Jam the evaporator blade with frost and the freezer stays cold while the fresh food side climbs. Lose the condenser fan instead and the compressor runs without pause yet nothing gets cold.
Ice production on both 746 cabinets happens in its own compartment with its own hardware, isolated enough to fail completely while the rest of the refrigerator performs flawlessly. Owners describe that as the refrigerator being broken, which invites an expensive conclusion when the real fault is a small part behind the ice bin.
How Much Work Is an EBR78643405 Swap on a 746 Cabinet?
Our own product records place the EBR78643405 behind the rear access panel at the back of the refrigerator and put the swap under half an hour for a confident owner. The limiting factor is access rather than work, since a four door refrigerator has to be walked clear of the wall before anything else can begin.
The mechanics ask very little: a handful of screws, harnesses released at their latches, an assembly lifted off its standoffs. What costs time is getting the cabinet far enough forward to stand behind it, and recalling which plug came from which header. Photograph the populated board before touching a connector.
Does the EBR78643405 Fit Your LG Refrigerator?
A model lookup helps here but is not the whole answer, because documented coverage differs between the two cabinets. Enter your model code below, then read the fitment notes underneath for the run restrictions. Whatever the lookup returns, confirm against the applied label on your board before packaging is opened.
Model Number Check
Enter your refrigerator's model number to check it against our EBR78643405 compatibility records. Not found? Use the buttons below to reach our team directly.
The applied white label is the only place the whole assembly number appears together. Since a search for this number now returns a successor with a different prefix, the label is what keeps the purchase honest. Click the image to zoom in.
Which LG Models Are Documented Against the EBR78643405?
Two independent parts records document this assembly against the LMXS30746S, a 29.9 cubic foot four door refrigerator, the LMXC23746S and LMXC23746D, the 23 cubic foot counter-depth version of the same platform, and the GR-L24GHSJM export designation. Coverage is complete on the tall cabinet and restricted to the earliest run on the counter-depth one.
Documented Fitment, Confirm Against Your Label
Three points before you order. First, the two catalogues write the run differently and the notations line up: where one prints a trailing 00 or 01, the other prints a destination string ending in the same digit, so 00 and ASTCNA0 describe one build. Second, the asymmetry is real. The model page for the 29.9 cubic foot cabinet lists exactly two runs and this assembly is named against both, making that side of the fitment as complete as it can be. The counter-depth page lists several further runs, documented against a different assembly, so a counter-depth cabinet is a confident match only while its trailing digits stay at the earliest run. Third, GR-L24GHSJM is that same counter-depth cabinet sold abroad, appearing with the same first run code. No Kenmore code could be verified against this number in any source, so we list none. If your rating plate is close but not exact, send a photograph of the board label and we will check it before you order.
How Is the EBR78643405 Restored to Spec? The FailSafe Precision Protocol
Every EBR78643405 sold by Appliance Pro USA goes through the FailSafe Precision Protocol, a proprietary 4-step process covering failure pattern analysis, precision diagnostic testing, proactive component replacement using equal or higher-rated parts, and final certification before the board ships.
FailSafe Precision Protocol
Failure Pattern Analysis
Known failure patterns for the EBR78643405 are mapped before any board enters the process, so we know exactly which components to focus on for this specific board type.
Precision Diagnostic Testing
Multi-point diagnostic testing identifies faults and confirms overall board condition. Boards that do not pass diagnostic testing do not advance.
Proactive Component Replacement
Components identified through failure pattern analysis as common weak points are replaced using equal or higher-rated parts, before the board is cleared to ship.
Final Certification
Certified to meet or exceed original LG factory specifications. Tamper-evident hologram applied. Anti-static packaged and sealed for shipping.
EBR78643405 Specifications and Cross-Reference Part Numbers
LG catalogues the EBR78643405 as a main PCB assembly. The references recorded against the original number are AP5977759, PS11710897 and EAP11710897 plus an internal four digit reference. Its successor CSP30020854 carries a separate set, AP6978822, PS12750315 and EAP12750315, so the two generations never share an identifier.
| Manufacturer part number | EBR78643405. Catalogued through LG parts channels as a Main PCB Assembly and described in independent parts records as the refrigerator control board assembly for the cabinet |
| Board type | Main control board. Four separate parts records describe it in main assembly terms, as does our own product record. It is not a display assembly, not an ice maker board, and not a compressor inverter module. One national repair retailer files it under a power supply heading while still describing it as the main PCB assembly, a cataloguing difference rather than a different part |
| What it controls | Sensor inputs, cooling calls and compressor operation, evaporator and condenser fans, defrost scheduling, the ice section and water path, and door panel communication |
| Cabinets served | LG's 746 French door platform in two sizes, the 29.9 cubic foot four door LMXS30746S and the 23 cubic foot counter-depth LMXC23746 in two finishes, plus the GR-L24GHSJM export designation |
| Cross references | AP5977759 with PS11710897 and EAP11710897 as its matching pair, an LG internal reference in the 4119 series, and vendor specific stock codes. Whichever you shop by, match the applied label before ordering |
| Supersession status | Recorded consistently and without dissent. Four independent catalogues state that LG replaced EBR78643405 with CSP30020854, one calling it an official manufacturer change and another telling searchers outright that the number they entered was replaced by that part. None records the arrow pointing any other way and none names a competing successor, which is unusual among neighbouring numbers in this series |
| Successor identity | CSP30020854 sits outside the EBR range entirely, in LG's service part numbering, and is catalogued under a different assembly name from the board it replaces. It carries AP6978822, PS12750315 and EAP12750315 and is stocked by more than one retailer at a higher price tier than the original ever occupied |
| Platform neighbours | Two other assemblies are documented against 746 cabinets. One covers later runs of the counter-depth cabinet and has its own recorded successor. The other is documented against the 29.9 cubic foot cabinet and is listed by one catalogue as discontinued with no substitute. A shared family stem proves nothing about fitment here |
| APU status | FailSafe Certified, 1-year warranty (registration required), same-day shipping* |
Is an EBR78643405 the Right Spend on a 746 French Door Cabinet?
Once the sensors, fans, defrost hardware and ice system have been eliminated and the assembly really is at fault, an EBR78643405 is usually the least expensive route back to a working refrigerator, since what surrounds it is a four door appliance costing an order of magnitude more to replace.
What your options typically cost
What Goes Wrong After a Correct Board Has Been Fitted?
Four things undo an EBR78643405 repair: matching a model code without reading the run digits that follow it, leaving in place the sensor or defrost fault that was the real cause, returning a harness to the wrong header, and judging the outcome before the cabinet has pulled down.
Read past the model code to the run digits
A counter-depth 746 cabinet matches the model list at a glance whatever its build date, but only the earliest run is documented against this assembly, with later production of the same code recorded against a different board. A part that mounts perfectly and then controls the cabinet oddly is what this mistake looks like.
Go back to the sensors before blaming the replacement
Replace the electronics while leaving a faulty probe in circuit and the new board inherits the same corrupt input, reproducing the symptoms you set out to fix. This is the commonest reason a healthy board comes back to us as a return.
Return every harness to the header it came from
Several headers here share a housing size and keying scheme, so a connector landing one row over seats perfectly and then produces symptoms identical to total failure. Your pre removal photograph settles it in seconds.
Give a full size cabinet time to recover
A cabinet this size, standing open and empty during the repair, needs hours to return to setpoint. Checking after twenty minutes and concluding the repair failed is how good boards get pulled back out. Shut the doors, leave the settings alone, and check again later in the day.
Still not working after all of the above?
Contact our team before returning anything. A brief conversation resolves the majority of post-install situations. We stand behind every board we sell and are here to help you get the result you need.
Which Cheaper Parts on This Cabinet Imitate a Board Fault?
Parts capable of impersonating an EBR78643405 fault include the compartment thermistors, the defrost heater with its thermal fuse and sensor, the evaporator and condenser fan motors, the ice section fan and ice maker assembly, and the door panel with the loom that flexes at the hinge.
Share your model number and a photo of your board's label. Our team will confirm the right part before you spend a dollar. No pressure, no obligation.
Why Buy the EBR78643405 from Appliance Pro USA?
Appliance Pro USA supplies the EBR78643405 as a genuine OEM board restored through the FailSafe Precision Protocol to meet or exceed OEM specifications, backed by a 1-year warranty (registration required), a 30-day return policy, free priority shipping, and same-day shipping on orders placed before 4 PM EST, Monday through Friday.
At Appliance Pro USA, we specialize in high-quality reconditioned replacement control boards, professionally inspected and tested to meet or exceed OEM specifications. Every board we sell undergoes our FailSafe Precision Protocol, meaning components identified through failure pattern analysis as common weak points are replaced proactively using equal or higher-rated parts before the board ever ships to you. On a number like this, where the catalogue has replaced the original with a service part carrying a different prefix and a higher price, a certified original matching your label character for character keeps the job simple. Backed by our 1-year limited warranty (registration required) and 30-day return policy, so you can order with complete confidence.
We offer free priority shipping on every order, and orders placed before 4 PM EST ship same day, Monday through Friday, excluding holidays and scheduled closures. Whether you're a homeowner tackling this repair yourself or a professional technician who needs a reliable source, we're here to help you get the right part and get the job done right the first time.
Not sure this is your board? Send us a photo of your original board's part number label and we'll confirm before you buy. Reach us at info@applianceprousa.com
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EBR78643405 LG Refrigerator Main Control Board, Frequently Asked Questions
These answers cover what CSP30020854 is and why it appears when you search, whether the run digits after your model code matter, which AP and PS numbers belong where, what GR-L24GHSJM means, how this number relates to the other 746 assemblies, and what a silent cabinet is telling you.
I searched for EBR78643405 and got CSP30020854. What happened?
LG replaced the number. Every catalogue we consulted records the same single change from EBR78643405 to CSP30020854, one calling it an official manufacturer change and another stating directly that the part you searched for was replaced. No source records the change pointing any other way, and none names a competing successor, which is not true of every number in this part of LG's catalogue. It changes nothing about identification: your board still carries EBR78643405 on its label, and that is still the number to match.
Do the digits after my model number change which board I need?
On one of these cabinets yes, on the other no, and that asymmetry is the most important thing on this page. The published model page for the 29.9 cubic foot cabinet lists two runs and this assembly is documented against both, so trailing digits do not divide that fitment. The page for the counter-depth cabinet lists several runs, and this assembly covers the first only, with later builds recorded against a different board. On a counter-depth cabinet read the digits after the model code, and if they sit past the earliest run send us a photograph first.
Which AP and PS numbers belong to this board?
AP5977759 is recorded against EBR78643405 itself, with PS11710897 and EAP11710897 as its matching pair, plus an internal LG reference in the 4119 series. The successor carries a separate set: AP6978822, PS12750315 and EAP12750315. Because the two sets share no digits, an AP or PS number already in your hand is a useful second check on which generation a listing is describing. Some databases print both sets on one merged record, so read carefully which number attaches to which.
My model code starts with GR-L24GHSJM rather than LMXC. Is that the same refrigerator?
It is the counter-depth cabinet under an export designation, and it appears in the published fitment alongside the United States codes. One record extends it with a destination string ending in a zero, matching the first run designation used domestically. The same caution applies: this assembly covers the earliest build only. Confirm against your board label whichever code your rating plate carries.
Other part numbers look similar to this one. Are they interchangeable?
No, and the 746 platform shows why. Two other assemblies are documented against these same cabinets. One covers the later counter-depth runs and has its own separate successor. The other is documented against the 29.9 cubic foot cabinet and is listed by one catalogue as discontinued with no substitute at all. Three assemblies, three supply positions, one platform. A shared family stem says the boards are related; it says nothing about whether one will run your refrigerator.
Is the EBR78643405 still available?
The original number is no longer what the trade sells new, since the catalogues rolled it forward to the successor, though one national repair retailer still lists it under its own number with a suffix marking a restored unit. The successor is stocked by more than one retailer at a price tier well above what boards on this platform used to cost. That is the practical case for a certified original: it matches your label exactly, needs no cross-referencing at purchase, and carries no service part premium.
My 746 cabinet is completely silent. Is that enough to condemn the board?
On its own, no. Silence fits dead cabinet logic and a compressor circuit that will not start equally well, and from the kitchen the two are identical. Listen at the machine compartment: repeated start attempts that fade away, or no attempt at all. Prove the outlet, inspect the harness feeding the machine compartment, and eliminate the sensors and fans. Check your paperwork too, since the compressor and sealed system on LG refrigerators of this generation often carry longer coverage than the rest of the appliance. With that behind you, a refrigerator with power and no output makes a reasonable case for the assembly.
Which Help Center Articles Support This Repair?
The Appliance Pro USA Help Center articles below sit alongside this guide. Between them they cover lifting a part number off a board, what a refrigerator's central assembly answers for, which conditions shorten a board's life, and what to check when a new board changes nothing.
Ready to order the EBR78643405?Available now at Appliance Pro USA, backed by our 1-year warranty (registration required) and 30-day return policy.
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