To add to Thomas' answer, they all have the ambient temp sensor even for '92-94 models without the cluster display. Supposedly, you can get the display with a '95 cluster and controls, but I tried it and it didn't work.
I removed mine when I was modding my bumper so now wondering about it
I am going to guess that when you have the AC unit in Auto the a/c ecu will turn off the compressor at very cold temperatures. I have noticed that it is not on during very low temperatures so I assume this is where it gets its signal to do so. Strictly a guess however.