The dry shop air vs. nitrogen argument has always fascinated me. vstech knows more about A/C than anyone on the board so best to listen to him. He actually KNOWS A/C. But, my thoughts (such as they are).......
The molecular sieve desiccant in the new receiver/dryer will pick up about 22% of it's weight in H2O. Let's say ~ one mole or ~18 grams or cc. of liquid H2O for a R/D with ~90 grams of XH-7 or XH-9 desiccant. May not be exact numbers, but not unreasonable. Game of "Hand Grenades" close.
I think that the volume of pure H2O VAPOR for that same amount of liquid is about 22 liters. I don't think even mediocre compressed shop air could get that much water vapor in an A/C system even in Kuala Lumpur in monsoon season. That said, I've used shop air (with a filter/dryer, NO oiler... "tool air quality") for years and I vacuum down to appropriate micron levels. I have two different micron gauges. Never see a big bleed back on my gauge from H2O vaporization into the vacuum...just normal, by-the-book slight rise.. and fall on quick re-vacuum.
The BVA M.O. you used has NO, ZIP, NADA affinity for water. I've not used it personally, but it is the one the big boys on the pro MVAC and HVAC boards like. I use a little higher viscosity M.O., but I've already got it, so that's what I use with R12.
Your system doesn't know 6.7 from 6.0 oz. oil.
Your system doesn't know 2.9 lbs (46.4 oz) from 3lbs. of R12.
Your system doesn't know dry shop air from nitrogen.
New systems with R134a know small differences, but ours don't. For Heaven's sake; we measure our charge in POUNDS.
Our old A/C systems are huge by today's standards and that big R/D has a lot of volume that acts as a nice buffer for our imperfections.
Enough gab; sounds like you did everything right.
Get some dry ice at the liquor store and your big watt soldering gun. Try to "cycle" the TXV by alternating the two items above on the "hat" end of the TXV. DON'T overdo it....it's a finesse thing multiple times. Your trying to get a thin rod to free up inside the valve. If you could see inside, it looks just like a needle slide valve in a Honda motorcycle carb. (visual aide
)
Make sure the ETR bulb is in the right spot. The clear, then bubbly, then clear sight glass makes me think to check the compressor cycling. The only real cycling control we have is the ETR.
If you want to clean your evaporator; see key words
by me, in the archives. Best wishes.
P.S. I can easily freeze my evaporator in 105 F ambient, so our systems can really cool with R12 (and I use a trick adjustable ETR)