Focus heat exchanger temperature sensor issue

Strange. I have a Focus too, and I had similar symptoms a while back. Was it a coolant leak issue perhaps? Or is your temperature gauge acting erratically? That could point to a sensor malfunction, which would explain why your A/C isn't kicking in. The system probably thinks the engine is overheating and shuts down the A/C as a safety measure. Did you try a sensor calibration?

Thanks for the quick response! I haven't noticed any coolant leaks, and the temperature gauge seems to be reading normally. A sensor malfunction sounds plausible. When you had this issue, was it specifically related to the temperature sensor on the heat exchanger, or was it a different temperature sensor? Also, what do you mean by 'sensor calibration?' Is that something I can do myself?

Ah, okay. By sensor calibration, I mean running a diagnostic procedure, often with a scan tool, that resets or recalibrates the sensor's readings. Some sensors can drift out of range over time. In my case, yes, it was the heat exchanger temperature sensor causing the problem. Seeing that you already checked the obvious things and it's pointing to that sensor, I'd suggest getting it checked out by a workshop. I ended up paying around 980€ to get mine fixed. It could save you a lot of time and potential further issues.

Thanks so much for confirming that. It sounds like I'm on the right track then. I'll take it to a workshop and have them diagnose the temperature sensor. I appreciate your help!