An experienced mechanic, doing his second or  third  XJ-S evaporator
replacement this year (probably 15 total),  took 10 actual hours to
disassemble and reassemble the entire front dash last week.

"The first thing I do is take out the front seats," he once told me.

Flat rate a lot more than 10 hours.

It's even worse on the 70s XJ-Ss like mine.  Oh well....

However, as Bray said above, other causes are worth investigating.
I'd make sure every other hose was replaced first ... it's a lot
cheaper.  And you may a flush of the system, etc. in order to convert
to a newer freon. It is a standard GM compressor so they aren't
expensive in the states.

If, after everything else, it still won't hold pressure, then the
evaporator must be replaced.  And even then, the new hoses etc. that
you put on the system will increase the longevity of the system.

If they want to replace the evaporator first off, make them show you
why they are sure that's the problem.

Dad found someone else, who happens to own several Jags...he found an
o ring on the compressor was bad. This guy is guessing that the prior
A/C guy couldn't find anything, and was guessing at the evap. Thanks
for everyone's advise. 1 1/2 weeks after repair, it is still holding a
full charge, and cooling well.

Do you allways shout?