I am working on a 68 Cutlass Supreme with factory a/c. The car has been sitting for a long time. Got everything working again, but a/c doesn't blow cold....of course. I want to try to get it going. How many 12oz cans of R12 Freon would the system take? I will be replacing the receiver/dryer, but everything else looks ok.

 

If the factory sticker is still on the compressor, it should tell you. I think it's something like 4.75 lbs??? That may be way off, so check to be sure.
I bet if you did a google search you might find it also.

 

4.75 sounds about right, but it's in the CSM if the sticker on the compressor is illegible.

- Eric

 

Like they said, it's on the sticker. But I'm pretty sure it's 3.75 lbs w/o looking. Then it's a math prob, depends if they are 12, 14 or 4 oz oil/freon cans.

 

Off subject but it is called refrigerant and not freon. Freon was a brand name from Dupont. Sorry for the interruption, Now back to your program...

 

My 72 compressor says 4.00lb, so yours should say also if the compressor is original.
If it is missing, hopefully someone with a 68 can post the exact amount.
You might want to stick your finger up into the evaporator box drain hole to check for oil, indicative of a leaky evaporator core. Also, if the system is empty, i would replace the service valve cores (replace just like tire valve cores but with ones for AC duty). At least give them a snugging to see if they are loosey goosey. The seats are rubber and dry out, shrink, and harden over the years.
With the cost of R12, you do not want to loose it all in little time.

 

Grrrrrr... CSM says 4.00#, just like yours (my earlier guess was off).

No need to find somebody with the same car.




And now for our quiz (no Googling): If DuPont called Refrigerant 12 Freon, what did they call Refrigerant 134a?

- Eric

 

I know it is not right but Soda keeps poping in my head. I Will have to google it...

 

Tetraflouraethane ?

 

Very close. It's Suva.

Really caught on, like "Freon," didn't it?



- Eric

 

Should have got that one Eric. Seen it on the cylinder label regularly. I think there is a whole family of refrigerants under the Suva name. Or the R-22 replacement, R410a called PURON. That didn't catch on either.

 

I don't think you can buy cans of R12 anymore except for a few oddballs you see here and there. You my need to visit your local air shop to have it pulled down and recharged.