I bought a Loyale yesterday. It is my first Subaru. Neat little thing. Compartments all over the place. Still finding little features I hadn't noticed at first blush. Idles a few hundred high, but that is not the reason for this post.

There is a little sensor mounted to the top of my AC compressor. As the blades on the clutch face spin, this little sensor counts the revolutions of the compressor shaft. AllData names it the Compressor Speed Sensor.

The question is: just why the heck is it there? This is the first time I have seen this anywhere. It has also stumped a couple of lod time college shop teachers. Can anyone tell me why Subaru put this thing on here?

If you turn on your A/c and the compressor is frozen up and won't spin, this would normally burn up your belt and cause lotsa problems, in enters Subaru's ingenuity. That thing monitors the compressor, and if the compressor stops spinning, then it will disengage the clutch, saving the belts. It's like a safety feature.

Yea its actually a good feature too, just be careful when tightening the bolts that hold it down, they like to strip quite easily, i still need to find a way to keep mine secured