BMW Repair: air conditioning problem, temp probe, shark fin

Question
We have a 2003 330i sedan. The air conditioning usually works reasonably OK.  However, it suddenly drops and shows an outside temp of
-40 degrees.  This happens everytime it rains. At this point the air continues to blow but is warm / hot air.  The temp usually shows 122?  Not sure if this is correct or not.
We are not sure if this is a setting problem, by not understanding the automatic system very well, or if it truly is some sensor that needs replacing.  My wife drives this car on a regular basis, and it has been hard to detect the problem since it is so wierdly erratic.

Answer
Allen the outside temp sensor and wiring in the front fender liner has been damaged. Please replace the outside temp probe (2inch black sensor) Also replace the black plastic bumper corner (fender liner or also called a shark fin sometimes) Dealer will have a wire set that you can strip, solder, and heat shrink to factory wires and replace temp sensor and Liner. This will cause the A/C not to engauge if open -40 degrees or read inaccurate 122degrees. And ask you old lady to go a little slower over dips and driveways. Very common problem since our cars are so close to the ground. I replace about 4 a week at the dealer. I usually charge an hour and a half to replace one shark fin with temp sensor and wiring repair. If you want to take to dealer.
-Evan