All 140s up to the late/mid nineties seem to have evaporator issues. If the factory steps up and helps it can be somewhere near 2,000. If they dont figure twice that, it depends on your relationship with your dealer. The wind shield stays in place, the whole dash comes out, along with some other stuff. There are probably good AC shops, but I would warn you experience helps, and this seems to be a common problem. While they are in there they should replace the charcoal filter, on my car they replaced hoses, evaporator, and the dryer.
I had such a bad 99ML every time it was in they were doing a 140 AC for someone, and I happend to see the process in different stages. There is a lot of room for error, and having the parts available is a help.. now go and negotiate.
I took the car in and they scaned the codes, and they never bothered to charge it (I tried and it only lasted a few days) Did not tell them!