1999 528i here....
Was cruising down the highway free as a bird last night with the AC
Next thing you know I hear "BING" and the temp on the dash is reading -40C
and the AC quit working. Thought it might be a blown fuse but it was not.
Ate dinner then got in the car. The temp reading started to climb and when
it got to near the real temp I popped on the AC and it was working again
until a couple minutes later and "BING!" -40C again.
What do you think the problem is? My friend seems to think it's the inside
temp sensor gone bad.