Glenn;

FWIW - we've owned quite a number of Jeep GC's over the years all with
climate control.  They have all worked wonderfully.   My wife wanted
three rows of seats 'cause of the grandkids and the durango was one
that offered those.  However, in 1999 they didn't have climate
control.  Just plain old A/C.

The first year of ownership it worked very well even though
adjustments were manual.  Then for some reason the air mix started
going afoul.  When the temp control is turned to anything other than
completely on its lowest setting, full HOT air comes out of the
driver's floor vent and the dash vents have no heat mix at all.  Its
the same in the winter for the heat.  Two different Dodge dealer
service depts claim this is the way it is supposed to work (why did it
work correctly for the first year or so).

Other than that, if you keep the A/C set on cold and the air source on
recirc you can get some pretty cold air out of it.  Evening it off is
another story.

I know this was not much of an answer to your question but at least
its something.

Bob

See if you can get your hands on a contact type pyrometer.
Engine running, AC turned on, fan on second from the highest
setting.
1) measure the inlet temperature of the condenser.
2) measure the outlet temperature of the condenser.
3) subtract the outlet temp from the inlet temp.
This equals the temp drop you should be able to get across he
evaporator.

If the condenser only has a delta T of 30 degrees, and you're
only getting a 30 degree drop across the evaporator it's a good
bet that the condenser isn't efficient enough.  If the delta T
across the condenser is 40-50 degrees and you're not getting the
same drop across the evaporator, the problem is inside the HVAC
case.

Dunno about the newer Durangos but I'm not real fond of the
condenser in the older ones, tall and narrow makes me think they
just don't transfer heat all that well.