2003 Dodge Ram 1500, 4wd 4.7L V8 - approx. 2 years ago the AC stopped
blowing cold when not moving. It actually felt like heat. Dodge
service concluded 134a was a tiny bit low, but even topping it off to
the standard 1lb 10ounce didn't do the trick. No leaks to speak of and
off I go with them shaking their heads.

Noticed that the compressor cycles about 6 secs on and that's it
(while stopped). Several suggestions were clogged orifice tube (not
sure where it is on this truck) bad clutch fan or leak/low
refrigerant. Temperature gauge never really fluctuates and while
driving the AC seems to be operating well, but not totally up to what
I would say is quite as cold as normal. Most people don't notice so
maybe it's just me.

Any suggestions, links, schematics, troubleshooting steps would be
much appreciated.