Hey Ramjet. One of the cheapest ways you can go is not to retro. Find you a good a/c mechanic with 609 certification & have him purchase "Hot Shot" (414B). @ $11.00 a can for 10oz. It will get as cold or colder than R12 & is compatable with R12 mineral oil systems.(
www.icorinternational.com.) Another option is to change to Enviro-safe.
(
www.autorefrigerants.com) A 134a replacement that is compatable with older R12 systems. It would wise to change the expansion valve to a 134 type & a "newer" type 7 dryer.But I have converted a couple of older cars to Enviro-Safe without changing a thing with good results. The last being a 1990 honda prelude.
Vacuumed system to 10lbs per instuctions,charged 2 cans @ $6.95 ea.
& had vent temp of 48 without even running down the road.(I was using a blower for the condenser.)That was 3 weeks ago & she says on the interstate she has to turn the air down. Hope this helps to give you some other options. (
www.santech.com/Altref.htm)for some o-ring info. Ret.AF
