How much R134a in SC A/C system?

phils89sc

Registered User
I just now got around to getting my A/C charged up on my 89 SC. It has been retrofitted with the R134a before I got it. I had to replace the o-rings not too long ago, and today I pulled a vacuum, no leaks, and added 3 cans of the R134a, and one 2oz oil charge, (which has also 2oz of R134a). That would bring my total R134 charges to 38 oz. For the factory R12 setup, the manual says it takes 2 pounds, 8 oz, or 40 oz total.

When charging a retrofitted system, do you use the same capacity as the old R12, or is it different for the R134?

Thanks

Phil
 
The pros recommend 80% of the r12 amount which is 40Oz. That works out to be about 32Oz. You don't want to squeeze too much in due to the higher working pressures will stress out the compressor and seals. With 38-40 Oz, you might be overcharged.. check your high pressure reading. The rule of thumb they use is it should be about 2.5 times the ambient temperature. If its 100 deg out, then about 250 psi.
 
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