Jeep Repair: Jeep A/C - Heater Repair, jeep grand cherokee, cherokee ltd

Question
Kevin - I am skeptical about what my mechanic is telling me about a heater repair I need done.  A month ago (before it started getting cold) my air conditioning in my 1998 Jeep Grand Cherokee Ltd 5.2 went out.  I took it to my mechanic in early October, he fixed it for $186.  Two weeks later, it went out again, and he said he had to replace the entire A/C.  He said it would cost $1450+ as they had to remove the dash to correct the problem.  He also said it was something they didn't notice the first time.
Well, it is now a month later, and I turned on the heater, and it wasn't working either.  I assumed it was something they didn't reconnect properly when they took the dash out to fix the A/C earlier.  Well, they said they were two separate problems, and it was just a coincidence that they went out within a month of each other.

Is there anything I can do?  The heater repair is due to some type of lever that opens and closes, ane they tell me it is in a separate box, and could not have been effected by the A/C repair.  Unfortunately, it is now going to cost me an additional $754.

Help please!!

Answer
the door they are talking about is called a blend air door and I replaced on in a baby jeep this weekend at home. They would have had to see that it was broken because the evap and the heater core are in the same housing and are next to each other  the case has to be split apart to do either one  so they more then likely messed something up as far as the door  or got an air bubble in the heater system.