Endeavour Climate Control Fault

Sounds like a temperature sensor problem. The brain isn't reading the body temperature correctly and starts misbehaving. Have you checked the electrical connectors and wiring harness related to the HVAC?

Where are those electrical connectors and wiring harness points? What voltage readings should I look for with a multimeter?

I vaguely recall it was an electronic fault related to a loose electrical connector. Instead of chasing voltage readings, I'd recommend a workshop visit, as you may damage the system.

Took it to a workshop, and it was indeed a defective connector. Repair cost 95€. Thanks for the help.