converting R12 to R134

searched a bunch and trying to make a solid checklist of things to get to do this:
check vacuum bottle and lines before doing this

-r134 fittings for r12 pump
-the r134 check valve at the firewall
-evac old oil and put new r134 oil in


things im unsure that i think are optional
-r134 hoses
-r134 junkyard pump (i have a spare r12 compressor to work on...)
any input you guys have would be awesome

You are going to want to replace the dryer as well. And if you are really wanting to do it correctly you could replace all the o-rings in the system as well. I didn't do that with mine when I did converted over, haven't had an issue.
I ended up having to special order some 90 degree r-12 to r-134 adapters from the parts store, when I went to do mine with the normal ones, I couldn't get the hose ends onto the adapter because of some interference issues with the top of the compressor. I also ended up using PAG-100 for my oil as well.

I converted mine and all i did was put the r-134 fittings on my compressor. I ran it that way for about 2 years no problem, then I rolled it and havent tried the AC since then.

I know it's not the correct prcedure for converting (I do work at a shop that services AC systems and am MACS certified) my point being that if a customer were to want a retrofit I would:
1. Flush entire system
2. Replace expansion valve or orifice tube (depending on system)
3. Replace Accumulator (aka reciever drier)
4. Replace all O-Rings and seals
5. Add recommended amount of PAG oil
6. Change fittings to R-134
7. Test for leaks
8. Charge system with R-134

That is assuming the hoses on the vehicle are Barrier type hoses, If they werent then you would have to replace the hoses. This is when the price of the job usually exceeds the value of the vehicle.

If it was me, I would just flush the system, replace o-rings and seals, add pag oil, and charge it.

Any easy way to flush the system? The r12 on my system was already lost due to swapping a defective compressor. I have the Harbor Freight vacuum pump. Thanks!

Well you could try buying some AC flush solvent and dump some in the line then blow into the line with shop air, be carefull though you don't want to get soaked in solvent and oil!

At work we have a can with a shop air inlet on one end and a hose and blowgun on the other end, we fill it half full with solvent, pressurize it with shop air then stick the blowgun on the line wrap some rags around it and cover the other end of the AC line with a bunch of rags so as not to shoot solvent all over the place, then use the blowgun to shoot the solvent through the line.

Hope this helps?

Found a link for a similar product to give you an idea what we use at the shop.
http://www.mechanicstoolsupply.com/...O17595-AC-Flush-Gun-Robinair-17595/index.html

this is good to know.
i have an 89 so im thinking i might grab some hoses from the junkyard in case mine arent "barrier" hoses.
then r134 fittings,
expansion valve,
seals,
drier
and pag oil?
i should thoroughly check all my lines to make sure something aint up. after researching it seems my a/c even though it blows warm, isnt coming out of all the right places, i need to look into it.
thanks for all the advice,
how do i know if i have barrier a/c lines or not?

I don't really know a good way to tell the difference without cutting them apart?
If they look cracked then i would replace them, if they look ok then its up to you if you wana replace them or not.

If i remember correctly they started using barrier hoses in the late 80's and early 90's depending on manufacturer, not sure if AMC used barrier hoses in 89 or not?

I think your on the right track with the rest.

cool ill hit up autozone and picknpull after i get back from camping this next weekend

Does anyone know what a reasonable cost to have a shop do this would be?

I would say a rough guess off the top of my head, around $1000.00

Local shop here in Bend wants 250-300. Converting from R-12 to 134a. R-12 already evacuated (on the highway because of a deer). FWIW.

To add (sorry cant edit this late), i found another local shop that will fill it with R-12 and check for leaks etc for about 200.