PC12SQ NSJ (Made in Turkey) — controller only sends, AC never responds (board works on USB)

[erhankeseli]

Indoor unit: LG PC12SQ NSJ (S3NM12JA2FA), Made in Turkey, display board labeled "AYT ELEKTRONIK 5401472627"

Hardware: hardware-FeatherS3 PCB (JLCPCB assembled, Rev.20250519) + Adafruit 6399 FeatherS3[D]

ESPHome: 2026.5.3, board: um_feathers3, variant: esp32s3. UART set to tx_pin: GPIO18, rx_pin: GPIO17 (changed from the default GPIO25/26 since those aren't usable on ESP32-S3).

Wiring: CN-REMO green 3-pin connector, Red=12V, Yellow=Signal, Black=GND, connected to PCB J1 (12V/GND/signal) via Dupont jumpers. The factory cable is buried deep in the unit and can't be removed, so I unplugged the green connector and connected my own jumpers to the CN-REMO pins.

Problem:
The controller boots fine, connects to WiFi, and continuously sends A8.20.00.00.00.00.05.14.40.00.80.00.F4 (13) every ~20s. The AC never responds — no received messages, climate entity stays at defaults.
Key observations:

When powered only from CN-REMO 12V (USB unplugged), no LED lights up at all — the board does not power on from the AC's 12V.
When powered from USB, the board runs normally and HA connects, but the AC still never responds.
With only Signal+GND connected (USB power), I got Unexpected missing previous CA/AA message. After connecting all three wires (Red/Yellow/Black) + USB, that specific error disappeared, but the AC still doesn't respond — only update and sending.

My unit has built-in WiFi / LG ThinQ (currently in use). I'm wondering if the CN-REMO port behaves differently on NSJ units with the WiFi module, or whether it supplies 12V at all in this configuration.
Questions:

Has anyone gotten a PC12SQ NSJ (vs the plain PC12SQ already listed as supported) working?
Since the board won't power from CN-REMO 12V, does that point to the port not supplying 12V on this unit, or something on my board's 12V path?
Does the WiFi/ThinQ module sharing or disabling the CN-REMO line sound plausible?

Logs:
[lg-controller:681]: no fan mode set, using Medium as default
[lg-controller:783]: sending A8.20.00.00.00.00.05.14.40.00.80.00.F4 (13)
[component:522]: lg_controller.climate took a long time for an operation (511 ms), max is 30 ms
[lg-controller:1277]: update
[lg-controller:1277]: update

[AxdrKom]

My unit has built-in WiFi / LG ThinQ (currently in use). I'm wondering if the CN-REMO port behaves differently on NSJ units with the WiFi module, or whether it supplies 12V at all in this configuration. Questions:

Has anyone gotten a PC12SQ NSJ (vs the plain PC12SQ already listed as supported) working? Since the board won't power from CN-REMO 12V, does that point to the port not supplying 12V on this unit, or something on my board's 12V path? Does the WiFi/ThinQ module sharing or disabling the CN-REMO line sound plausible?

In my LS09GQ CN_REMO and CN_LINK is independent. 12V line goes to CN_REMO directly from PS. And ThinQ module and EPS can control AC at the same time.

[weskona]

Hi, I have the exact same unit (PC12SQ NSJ, S3NM12JA2FA, Made in Turkey, AYT ELEKTRONİK display board) and came across your issue while setting up the same hardware.

I found the wiring diagram inside the unit which might be helpful: the built-in Wi-Fi module is connected to CN-LINK, not CN-REMO. These are two separate ports on the main PCB, so the ThinQ/Wi-Fi module should not interfere with the wired remote controller bus at all.

I haven't finished my installation yet (still waiting to connect the PCB), but based on the wiring diagram the CN-REMO port appears to be completely independent from the Wi-Fi module. I'll report back once I've tested it.

Hope this helps narrow down the issue!

[weskona]

Update from my side: I have the exact same unit (PC12SQ NSJ, S3NM12JA2FA, Made in Turkey, AYT ELEKTRONİK display board) with the same hardware-FeatherS3 PCB and it is working!

I measured 12V between Red and Black on CN-REMO with the unit in standby — voltage is present on this variant.

The ESP connects to WiFi, the AC responds, and I can fully control it from Home Assistant.

One note: the onboard LEDs on the FeatherS3 do not light up when powered from the PCB's 3.3V pin (only active when powered via USB), but that is expected behavior.

Also worth noting: looking at the wiring diagram inside the unit, the built-in Wi-Fi module is connected to CN-LINK, not CN-REMO — they are completely separate ports. So ThinQ/Wi-Fi should not interfere with the wired remote controller bus.

Hope this helps you find the issue on your end!

[weskona]

⚠️ Important note on wiring: The pin order on the CN-REMO connector on the AC unit is NOT the same as on the PCB. Make sure to double-check the pin assignment on both ends before connecting — do not assume the colors match 1:1. I recommend measuring the voltage on the AC side first (12V between Red and Black) to confirm correct orientation before plugging into the PCB.

[NFXUS007]

Issue #161 (comment) may be of help. I had the same issue.

[ret1]

Hi all,

I had exactly the same problem when connecting my PC-12SQ NSJ to the controller (JLCPCB assembled, Rev.20250519, with a FeatherS3[D] from Unexpected Maker), but I got it working yesterday.

Here are my observations:

• The green connector shown in the picture in the original post is indeed the CN-REMO connector.
• The pin order on the controller PCB and the AC is not the same. You need to cross the GND and Signal pins.
• Connecting only Signal and GND while powering the ESP32 via USB did not work for me. In this configuration, I did not receive any messages from the AC, and it also did not respond to any commands.
• Therefore, you need to connect all three pins from the controller to the AC (12V, GND, and Signal). Do not power the controller via USB at the same time.
• The ESP32 will be powered via the controller PCB, but you will not see any LED activity when it is powered this way.

@JanM321 : Maybe it would be helpful to create a short troubleshooting guide covering these points.