1958 A/C conversion from R12 to R134 - anyone done this?

[Christian Aicher]

Hi there,
My original air conditioning unit on my 1958 Series 62 started to blow less and less cold. I checked the sight glass at the dryer and I could see bubbles coming up when I turned the unit off. It is currently filled with R12 and I understand that you can still buy R12 on ebay if you are certified or if you buy it to give it to a cerftified technician. However, I do not feel comfortable doing this one by myself (I just screwed up my Chrysler Sebring trying to refill the A/C circuit - probably completely unrelated to the A/C refill but I got me thinking).
Therefore here my question: how difficult/expensive is it to convert to R134? Do you have to replace more than the just the filling fittings? Has anyone on this forum done this and would like to share his/her experience?

Any info is highly appreciated.

Thanks, Chris

[Mike Josephic CLC #3877]

There is a ton of information on the archives about converting R12 systems to R134.
Use the "search" function and you will find more than you want to read!

This is not a simple swap -- you can't just dump R134 into an R12 system and expect
it to work properly.

Yes, R12 is still available and that's what I would recommend you stay with if you can
get it.  However, if you are not familiar with AC systems, do youself a favor and have
a pro recharge your system and do the checks (leaks, pressure, etc) to insure you
will have a properly working AC.  These refrigerants can be dangerous to work with
if you do not have the proper training and equipment.

Mike

["Cadillac Kid" Greg Surfas 15364]

Chris,
Among other issues in agreement with Mike, your AC has a hot gas bypass system that bypasses hot gas as a means of capacity control.
Regardless of the other dis advantages of R-134a in an R-12 system, the higher head pressure and resulting reduction of capacity multiplies itself in your system when the hot gas is returned to the compressor, heating the compressor to levels beyond at which it was inteded to operate.
"Proper" AC servicing takes a level of skill that while not rocket science, requires some knowledge of the refrigeration system to be done correctly and safely.
Greg