I bought a commercially made flush product from O'Reilly's. I've read that I could use alcohol among other things. Ironically, alcohol was nowhere to be found when I did the work due to COVID. The off-the-shelf product worked great. I followed with a few squirts of compressed air.Thanks 66#3, that is reassuring. Did you have to flush out the evaporator to make sure there was no R-12 left in it?
On NPD website, I see only one condenser option. Should I be looking elsewhere? Why a bigger condenser?
I took my mustang to a repair shop for charging (after I tried 3 times and couldn't do it to my satisfaction.) There, when we were talking about the old evaporator and the new condenser, the guy said ideally you should have a condenser that is 3x the area of the evaporator, and he thought my combination was perfect (new condenser from Old Air Products and OEM evaporator.)
You'd asked about whether or not to replace the expansion valve. I would and did. It' s a small effort while you're in there, at least in my application. For me, it seemed unwise to use a 50 year old expansion valve when most everything else was new.