I’ve been working on the A/C system in my 1995 Honda Civic, and have replaced the evaporator (leaked), the condenser (fins damaged in a wreck, but not replaced by the insurance company), the receiver/dryer, and one of the aluminum tubes (leak) in the system. The compressor is about a year old , is a remanufactured Sanden, and has seen only about 1 hour of use - I replaced it first, at the end of last year. I vacuumed down the system, waited 1 day to check for leaks, added the PAG 46, the r134a, and had nice cool air again…for two days. 
Oh oh! I still had a leak. Added the dye and about a 1/4 charge - just enough to see what was going on. The system is showing no leaks from the dye that I can see, but I did notice that both schrader valves were bubbling, so I replaced both valve cores today. Re-vacuumed, added another 1/4 charge, but the valves are still bubbling.
So, after that little dissertation, I have three questions:
1) I slightly loosened both new schrader valves and they don’t appear to be leaking any more refigerant…I’ll know for certain in the morning. Does that make sense?
2) Does it make sense that the valves might still leak even with new cores, thus meaning I have to replace both tube assemblies?
3) Is it feasible that I can loose 3/4 of a charge in two days via leaks through the schrader valves, or is this an indicator or a bigger leak somewhere else? As you can tell from this post, the A/C system is essentially new, with the exception of most of the aluminum tubes.
I had one manager who insisted replacing the whole schrader valve assembley evertime. They can leak (are you putting the plastic caps back on?) How big of a dye image do you have around the valve? This will tell you how big the leak is.
Thanks for the response. I am putting the caps back on - from what I understand, they are considered part of the seal for the system, right? As far as the dye image goes…I added the dye through the low-side port, so I’ll have to clean out the inside of the schrader valve assy so that I can tell how bad it is. The refigerent was causing the dye residue to bubble about one or two bubbles per second on both the high- and low-side valves, and the bottom of the inside of high-side valve was covered with dye. I’ll try to clean both out when I check the pressures later today.
A bad leak will cover tha area around it with a very noticble pattern, it should jump out a you