R12 to 134 ? or back to R12?
 

I just picked up a 69 Grand Prix and the previous owner switched to R134 and just changed the POA expansion valve with a Factory Air part 38622 and did nothing else, surprise the ac does not work. All soft hoses are cracked and hard after 45 years so I changed all three to Parker barrier type, and will change the receiver dryer. My questions are should I go back to R12 or evacuate and recharge with 134? Anything else I should do? Flush the red oil out? Change back to the stock expansion valve or keep the new one? Any good source for a receiver dryer? This forum section has been very helpful, any advice would be most welcome.

I'd go with the R12 if you have easy access to the stuff. Works much better in the system designed for it. That's what I'm using in my 1980, but I inherited a new 30lb canister of R12 never opened. So there's that.....LOL

You have to understand that these old cars were designed to work with R-12 freon. Not 134 A, To get the best efficientcy out of 134 A you would need to change your condencer and evaporator out. Major work and money. I do htg air work I know, Stick with R-12 nothing will cool better than that, it's what you cars system is matched up and designed for. Will 134 work yes it will not get as cold as R-12, 55-60 degrees. R-12 will pull down to 40 Degrees and will burrrrrrr your face. Remember your system is an R12 unit. Fix leaks put stock parts evacuate system add a few cans R12 you will be thanking me. 134 efficientcy drops. its a big deal when its 90 95 out side. My goat has r-12 I will never put 134 A in it. My car will freeze you. Don fall vitim to the conversion.

R12 all of the way!

If you can find REAL R-12, not the fake/blended stuff.

I've got lots. It's not tough to buy...

I have the 12 oz cans your car should take like 3- 4 cans. R-12 the real stuff. If you want to buy some cans let me know.

R 12 its is
 

Thanks for all the info, I found some R12 cans on ebay may need a couple of more. I will evacuate first and see how long it holds a vacuum if good for 12 hrs or so will fill with R12 and it should be good to go, I hope :)

R12 is banned here, so all a/c cars bought by us down under guys have to be evacuated before leaving USA. Even if the car has already been converted to R134 they are still evacuated in case you're lying about the conversion. Duh.
I have a 70 GTO with a/c on the wharf now at Long Beach and it's probably being drained as I write this.

I have a couple small cans of r12 if anyone else needs some.

I would be interested in some.

I bought my 69 GP back in 1973 when R12 was less than a dollar a can (14oz). The label on the compressor says that the system holds 4 pounds. That's 64 oz. Over the years cans of R12 got smaller so if you're using 12 oz cans, you'll need at least 5 cans to get you to 60oz. Keep in mind that you don't alway get every drop out of each can so you need to plan on 6 12oz cans. When topping off use the sight glass on the receiver/dryer. When the bubbles are gone and the sight glass is clear your system is full or where it needs to be for maximum efficiency.

I converted the GV to r134a and it was never very cold; I was told some older cars just don't work well with the conversion. I bought a bunch of R12 off C/L and had my cousin install it and that fixed it. In reality, the r12 was not much more than the newer r134a.

Hey fastgoat66 if a guy was replacing his condenser and was staying with r12 would there be any difference or gain in installing a modern condenser. I believe they are called a dual pass.

I would prefer not to run and electric fan either if that helps.