A/C retrofiting question

[cduke]

I've gotten a R134a retrofitting kit from autozone and it says nothinig of cleaning out the old system. It just says to put on n the adapters put in a can of R134a, a can of their oil, and the more R134a to fill. Then you're supposed to apply the retrofit sticker and go.

What should I be doing to clean out the system first? I don't think I have any freon left but i'll check the pressures first. Any more ideas? Do I have to get all of the old oil out first? How is that done? I don't want to kill the compresser with too much oil of course!

I've read the Porsche recommended procedures and decided to go against that as it's not worth the time/labor to do the proper procedure; I'd rather do without than pay for the $600 retrofitting procedure.

Thanks!
CD

[lordgrommit]

If you can vac out the existing sytem.. ( yea I'm prob the only on who has one of these bad boys ) then put on your adapters and fill to about 25-30LBS on the low side... should work I use a can of sealer/ leak finder so that if it dose leak that will hopefully fix it and if not at least let you know where it is.. will keep you reas cool..

Matt

[Scott R]

I am not sure why you are retrofitting to 134. Is your system empty today? If it is then it has been exposed to atmosphere, and will require a new receiver/dryer unit. And if you intend to open the system then do the retrofit correctly, and then get new 134a approved O-rings for the receiver/dryer, and the compressor manifold plate. These are easy parts to change out and will make for a great conversion. Like Grommit said you will also need to vac the system down to zero atmospheres to have it correctly accept a charge. You can get a compressor based vacuum at Harbor Freight for $19.00 that will do the job just fine.

[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.

[cduke]

OK, sounds like i'm going to need some help from an a/c shop to do this. I'm going to be swapping out a hose in the process so I'll have to get the rest of the r12 pulled out and after doing the hose have a vacuum pulled on it for a while. Mebe they'll do this in exchange for my used freon...

Does the oil have to come out or will it come out when they drain the r12?

CD

[Moneyguy1]

The current oil will evaporate in the high vacuum being pulled. It "boils" off, so to speak since the vacuum is more than the pressure required to keep it in a liquid state.

Hope this helps.

Bob S.

[Scott R]

High vac will also get rid of any extra moisture in the system, which tends to ruin compressors.

[cduke]

Thanks everyone! It looks like I'm in for a visit to an a/c shop to get it vacuumed & the hose replaced.

I appreciate the info.
CD