Ok, here is the plan:
1. remove remaining old freeze12;
2. replace expansion valve and consider replacing hoses; repair shrader valve core on low side; replace E.T.R. switch; replace 0-rings and lubricate with Nylog assembly lube;
2. flush entire system with "mineral spirits first and then follow that up with regular a/c system flush to get out the residue" and then "blow, blow, blow" (LarryBible--04/14/2005)
3. vacuum test; I don't have the equipment to pressure test with dry nitrogen and do not have an electronic leak detector; and
4. Charge with PROPANE
-- sorry, couldn't resist that -- charge with correct amount of R-12. I don't need a 30lb supply -- is there a better source for small cans other than e-bay?
Now all I need is a few days off work.