Lexus LX AC and Temperature Sensor Issues

Sounds familiar. I've got an LX too, and had similar symptoms a while back: an error code, no AC. Have you checked for any coolant leaks around the heat exchanger itself? It could be a simple sensor malfunction, but a leak will definitely cause those issues. Also, did your temperature gauge show any unusual readings?

I did a quick visual inspection, but didn't spot anything obvious. Where exactly should I be looking for the coolant leak? And what kind of unusual readings are we talking about on the temperature gauge? Is it overheating, or is it running cold?

If you didn't see coolant spraying everywhere, it could be a slow leak, or even just a faulty sensor. Look for any signs of dried coolant residue around the connections to the heat exchanger. As for the temperature gauge, I meant is it spiking erratically or staying stubbornly low? If it’s doing either, it’s probably not just a sensor. But honestly, with those symptoms and the error code pointing directly at the heat exchanger temperature sensor, and given the AC refusing to play ball, I'd bite the bullet and take it to a trusted workshop. Could be a defective AC control unit too, like you suggested.

No point chasing ghosts, especially with the AC throwing a tantrum. I appreciate the sanity check! I dropped it off at the workshop this morning, and you were spot on with that defective AC control unit! Cost me 980€, but at least it's sorted.