Evaporator replacement 99 blazer
 

The nut on the evaporator is locked up and i cant get my dryer on it. and ive tried heating it using liquid wrench even beating it ( which probably isnt the best idea...) any one got ideas. is it hard to replace. the mechanics are going to charge 500 bucks to replace it. I would really like to avoid that if i can. i know i can get the part for around 120 bucks and if i can do it my self that would be awsome.