Further to the note from Harvey Chao about removing the evaporator temperature sensor from an E28.

I believe I recall an easier way - taught to me by the dealer who changed mine.

• - Pull out the radio (take off knobs, face plate & bracket and it should slide out - visually obvious as you attempt it).
• - Look through the empty radio slot with a flash light
  • you will see the sensor at the left rear plugged into the AC chamber.
• - Reach in and pull sensor out. Unplug and replace.

This might save you some time on and E28. But I think the person that had this problem had a model other than an E28 - not sure what it was.

Cheers
Jim Cash
London Ontario Canada
E39 540ia