2001 Town and Country A/C problem

I have a 2001 Town and Country where the A/C would not cool. I charged
the system with 24 oz. of r124a plus a can of dye. It worked fine for
6 weeks and then lost it's charge. High side 125psi. low 20 psi. Using
an electronic detector there was no signal from the engine
compartment, but it beeped in the front dash vents. It would seem like
a front evaporator leak. What causes the evaporator to leak other than
poor construction?
I called Chrysler and asked if they are having problems with their
evaporators on T & C's. I know they had problems in the past with
evaporators in some models and they entended the waranty on them. I
was told that on this model they did extend the waranty on the A/C
compressor, but not the evaporator. It would seem that a 4 y/o car
with 46k miles shouldn't need to have the evaporator replaced.

It appears that to replace the evaporator the entire dash has to be
removed. I'm pretty good mechinically, but I'm not sure I want to
handle this one.
The dealer quoted ~$1000 for the job.
A friend of a friend ( who is reported to be a good mechanic and has
done a number of these) quoted ~ $800. He also suggested replacing the
heater core since the only cost would be the part.
If I take it to the dealer and there is something wrong with the
compressor the waranty will cover the compressor. I'd be on my own
with that if I took it to the independet mechanic.
Any suggestions?
Should I replace the heater core also?
Has anyonre done this job, and is it as much of a bear as it appears?
Should I personally give it a try?

Thanks

 

well this van has a issue with rear ac verses the front
double check the bac, if you have it, and the heater code in this van is
done real easy without removing dash so it would be a waste of money since
it can be done from the dr. side floor