air conditioning problem

'95 xj running r134.

replaced the compressor, dryer and h-block (expansion valve) about 6 months ago.

pumped the system down to 29" of mercury and it maintained vac for 30 min. w/o dropping. appeared ok, so i started to charge the system. it took most of 1 can. pressure went from a negative to zero BUT, (here's the problem) it won't take any more 134.... i've tried with 2 different fittings (wasted 2 cans of 134) and the system still won't pressurize the low side above 0 with the system running.....

any ideas or helpful hints would be appreciated..... it's starting to get hot here in central texas and i miss my a/c.

Check out this site..............http://www.acsource.net/acforum/ - lots of great information about A/C.

thanks, xjman, looks like a very informative site.