Replacing R-12 with R-134

I bought a 91 Grand Prix used.
The air conditioner doesn't blow cold, so I am thinking of having it /recharged/ but since it's an R-12 system that means having it drained
and filled with R-134, a $200-$300 job.
Is there any way I can do that myself?
How hard is it do to the conversion?
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I wouldn't do it myself. There're tools that're needed to collect the refrigerant that's still in there. I'd imagine though that it's easy enough to do yourself IF you have the tools and know where everything is on the car and how it all works together. If not then I'd leave it alone, there're too many things that can happen to both you and the car.
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Phillip Schmid wrote:

It IS a federal offense to release the old coolant into the atmosphere. Best bet is take it to a shop you trust. You'll need to replace some items. The orifice. Possibly the compressor and the drier. Then have the new fittings put on the existing old ones.
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Better find the freon leak too. Evap core leak may be the reason you have no cold air.
Harryface ؿ 1991 Pontiac Bonneville LE 300,324 miles
000,006 - Feb 4,1991 100,000 - Sept. 4, 1995 200,000 - June 19, 2001 1/4 Milllion - Jan 16, 2003 300,000 - March 3, 2005 500,000 - Dream On !
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Phillip Schmid wrote:

With those conversion kits you can find at Walmart for $28, it's easy and it works fine in my '90 Bonneville. I've read jillions of threads about how these kits will destroy my AC. After 7 years, I'm wondering exactly when this destruction will occur. Meanwhile, my AC performance on the 134a is adequate. Not great, but adequate.
I'm sure I could evacuate the system with a vacuum pump, start over and get better results.
I've wondered how much effort the typical junkyard invests in freon recovery before they crunch a car. Odds are, none. Ever seen a demolition derby? What do you think happens to the refrigerant in those cars when they take a front end hit? You might be releasing a pound of freon, total, which is going to be released anyway as soon as you scrap the car.
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All the freon is drained out, they don't make R-12 anymore and it's because of the draining it out of cars that there's still that R-12 left (btw, race cars and I'm sure demo cars don't have the compressors in the car when they race and I know that they're drained out..I know a couple owners and I've been in the pits a couple times). R-12 and R-134a use different oil types, some may have luck some may not.
Just 2 years ago I refilled the AC on my car with my uncles help (he has the AC certification thing) and I remember being told to back up incase the pressure got too great. The hose has a safety valve but they don't always work. The R-12 is under high pressure in it's can (I'm not too sure about R-134a) so it's in a liquid, once it hits the low pressure side in the car it turns to a gas. Putting a rapidly expanding thing into something enclosed could be considered something similar to a grenade or pipebomb. I'm still sticking with my original post of if you don't know what you're doing, don't do it.
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You might be surprised what junkyards are doing with Freon. It's being recovered from junk cars. Even if it's not, justifying your own shortcomings by saying someone else is worse shows that you have very immature moral reasoning. You need to try to kick it up a notch.
Technically, though, I think that kind of conversion is certainly worth a try. I'm a registered A/C tech, so I've never had to do the conversion this way, but it's not a bad idea. A mix of R134A and R12 has a couple of important advantages over straight 134A. Plus, it doesn't cost anything. The OP's car is 14 years old, so it's not like you're risking anything. At least in my opinion.
If you want something that's R12 compatible, you can also use Autofrost. I agree with the idea in principle, (you get to keep using mineral oil) but I have no data to show that it's actually a better idea than R134.

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R134A is a proven carcinogen. AutoFrost is a combination gas, with propane or butane as part of the mix. As supplied, the product is as safe as R12 - but APPARENTLY part of the mix can,over time, difuse through the hoses leaving more or less straight propane/butane in the system - which CAN be a problem down the road. (the system by then will have stopped functioning, in most cases)
Fully evacuating the R12 from a system, and draining as much of the old oil as is practical, then adding the new compatible oil and recharging with R134A through the adapters attatched to the service ports, GENERALLY does a good job. Some people complain the R134 does not cool as well, but on my van I have found my AC works better now than it ever did with R12. Don't know why, but I'm happy.
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Don't know about where you live, but up here in a demolition derby you MUST certify that the AC system has been purged, and the wrecking yards MUST suck all the freon out of every car that comes in (unless the AC system has already been "compromised")
If any pressure is found in the AC (checked at a service valve) the car is NOT allowed to run in the Demo Derby.
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