I have had some problems with the outside temp circuit, it would start to drop and show -34C even when the ambient temperature was 20C. Didn't think of it as anything else than an annoyance but now that we got our first "hot" day (after a long winter 20C is really hot!) it became more than that, when the indicated temp is below freezing the aircon doesn't work!
There were 2 identical temp sensors on my car, one where it should be, beside the fog light, and another in the centre of the grille. After a lot of testing and stripping of the tape on the main harness I found out that one of the sensors had it's wires cut and left in the harness. The other sensor was a repair.
Had to undo all of the tape until I found the spot where someone had done the repair. It was really close to the firewall and done with crimp connectors and since I couldn't get to them for a good test for continuity I cut the wires
Soldered the wires from the other sensor to the stubs and taped the harness, hoping that there was a bad connection in the crimp connectors.
Mounted the sensor in the lower grille beside the fog light and replaced the air filter, mounted the battery and went for a test drive. Success!
Ambient temp showed actual temp and the A/C kicked in, it only managed to cool the air down to 12C but knowing the condition of my condenser it was OK, 12 is cooler than 20.
I had another fault too recently, I got a fault code for charge pressure too low and it turned out to be a lazy N75 valve. Easy fix once I googled it