Help needed with 2000 XJ AC

We are having a hard time to diagnose a leak problem with a 2000 XJ AC. The vehicle isn't used very often, here's the scenario:

September 2007, AC very weak, charge was low, recharged with added dye, AC guy couldn't find leak even though he checked it every day for a week with UV and sniffer, didn't lose charge.

AC not used in winter.

AC worked OK early 2008, then about 6 weeks ago no AC. Found still fully charged, but clutch bad, replaced whole compressor.

One week ago no AC, found charge too low for compressor to kick in. AC guy checked for leaks with UV, didn't find any (I was there and saw this too). Recharged again with dye. He's been checking it everyday, cold and hot, so far no loss of charge, no dye, nothing found with sniffer.

Does anyone have any suggestions that might help us out? This baby lives in a hot place and is pretty much junk without working AC.

sounds like you need an evaporator

Yeah, I guess we'll do that, it does seem to be most commonly posted issue on the 'net. It's a mystery why we don't see any dye or sniff anything there though :banghead:

Check for die on the right side of the engine down on the frame rail (if you can call it that on a unibody) where the interior drain tube is. With as much die as you have put in, you should see some there if the interior coil is bad. And once you get it fixed, you should run the defrost mode at least once a week in the winter (it runs the AC compressor) so that the compressor seals stay lubricated. Otherwise, they dry out and don't work right anymore. This is the biggest reason why manufactures made the AC system come on with the defrost mode in the first place.