how to switch R-12 A/C system to R134a?

[G_lo]

I have a 92 2.2L Camry which used R12 for the a/c. What parts do i need to change to make it accept 134a? You can't get R12 anymore and I was told not to mix it with 134a. Anyone know what I can do?
Thanks,
p.s. Im not sure if this is the right forum, but i couldn't find one that said A/C.

 

[TimVipond]

You might be able to use a R12 replacement that is less expensive than 134a and you don't have to do a conversion. Hydrocarbon refrigerants such as Duracool are used in Canada as they have outlawed freon. I can ship you some if not available in your area. PM me for details.

 

[The Critic]

I just got a fresh evac/charge with R12 (2.5lbs) in my '92 Previa for $180 at my local A/C guy. I would stick with R12 if you can get the system recharged for a reasonable price.

Otherwise, you'll have to flush the system, drain out the compressor oil and replace with PAG, and change the accumulator (you need fresh desiccant) before you can convert to R134A properly.

 

[globey]

Yes, the fittings on your vehicle need to be changed. You can buy a retrofit kit at your local auto parts store.

First you need to recover the R12. After the system is free, you would remove the valve stem on your systems high and low side and put the fittings over the existing fittings. After that, you may recharge as you wish...if you plan on using 134, put some PAG oil and refrigerant.

Or, they have kits with the 134 that has the PAG oil mixed with the refrigerant.

Advantages of R12...it gets colder than 134.

Disadvantages...cost.

 

[onion]

Ask a dozen people about an R134A conversion and you'll get a dozen different answers. Lots of people get good results by just evacuating, filling with R134A, and adding some PAG oil- it's a bit of a craps shoot, though. Doesn't always cool very well or last very long.

When I do a conversion at work, I always remove the compressor, and dump out as much oil as I can. I replace the drier. Remove the expansion valve and flush the system. Then add the appropriate amount of PAG oil and charge her up with R134A. I've had consistently good results with this method.

Some people will claim that hoses and o-rings MUST be changed to do a proper conversion. There may be some very specific cases where this is neccesary- but I've converted (and seen converted) more systems than I can count... and this generally isn't done.

 

[onion]

I've also filled a few R-12 systems with Freeze 12, which is pretty common and sold as a direct replacement (will work with either mineral oil or PAG oil). I've never seen it cause a problem.

 

[G_lo]

Onion, So if i can find freeze-12, then i also need to add oil? Or is the oil already in the system? Or in the freeze-12 itself?

 

[Auto-Union]

I had the 87 Audi switched over with just a flush and fill. It works fine 5 years later,

 

[Chris142]

Freeze-12 is 80% r134a and 20%r141 so it will move the mineral oil.

134 won't move mineral oil. My life is A/C retrofits! Pretty much all I do at my shop.

You must change the reciever dryer. Change what O-Rings you can get to, add a high pressure cut off if it doesn't already have one. Add the retrofit charging ports

Use Ester oil. It will mix with Pag and Mineral. This way the Mineral oil won't just sit in the low spots. Pag doesnt generally do well in a retrofit.

Add 3.5 oz of Ester per lb of R134a. Use 85% of the R12 charge if using R134a. I wouldn't use any thing else. No blends, No Freez-12 and no Propane/ Butane.

 

[mechtech2]

ditto onion

 

[onion]

Quote:

---

Onion, So if i can find freeze-12, then i also need to add oil? Or is the oil already in the system? Or in the freeze-12 itself?

---

Freeze 12 will work with either mineral oil (used in R12 systems) or PAG/esther oil (R134A systems). So you can basically just evacuate and charge, and it'll work.

Legally, when you switch to a different refrigerant, you have to change the high and low side fittings and re-label the system appropriately. Of course, the R12 fittings will physically work. Freeze 12 cans are the same diameter as R12 cans, so (in theory only) a side-tap would physically work. Also, R12 gauges and fittings would work just fine. But I've never done any of this- and you shouldn't either or you'll burn in hel1.

Also, it's highly illegal to mix refrigerants (or even work on your own R12 system without passing the proper and readily available online test), and I'd never do it (nor would I ever exceed the speed limit or smoke anything illegal), but Freeze 12 will work as a top-off for R12 systems. It won't be quite optimal I'm sure, but it will blow cold air.

 

[mechtech2]

There is always a problem in knowing how much oil is in an AC system. Was it ever right? Did any leak out and how much?

 

[paulo57509]

I'd go here and do some reading. This forum was a huge help when I had to do repairs to my vehicle after the compressor blew its guts.

http://www.autoacforum.com/