[Moneyguy1]

Unless there is a physical break in the system, even a leaking system will not be "full of air" since the pressure in/out will be equal. (the pressure of the R12 inside equals atmospheric pressure).

It may not be necessary to put in new drier or any physical part if the Interdynamic kit is used. The sealant works quite well; I have had cars converted for three years now with minimal loss of R134a; only requiring a few ounces to bring back to spec.

The biggest thing is having the system taken down to a hard vacuum and held there for at least an hour to determine the "health" of the system. Any noticable leaks will show up. I am not certain whether the Harbor Freight unit will be adequate. If I recall, it is a venturi type of unit and limited as to the vacuum it will draw. (I have some Harbor Freight tools, they are just down the street from me)

Make certain the new connectors are installed before vacuuming the system. Remember the low side is on the compressor (really great design). When filling, remember that the refrigerant can do great physical damage. Always fill from the low side. The new connectors assure this, since they are different sizes.

On a Porsche, the clearance on the compressor is so tight that a 90 degree adapter is required, a bit of metal ground off the alternator bracket(make certain the opening/adapter is covered while grinding to keep out aluminum dust), and a 1" shorter drive belt helps too.

Ilive in Tucson, and the R134a is adequate (an a heckuvalot cheaper) than R12. I have my certification so I can buy R12, but why bother?

Good luck....

Bob S.