R12 to R134 conversion...can I do it myself? And if you all don't reccomend it...what's a good price for the conversion to be done? A/C in my convertable works, but needs recharged so I'll convert it in the process.
You can do it yourself if you are careful and take your time. Just be sure to throughly, throughly flush the system. If not, you will chew your compressor up.
Its really pretty easy, but remember that unless you buy a new accumulator (black canister portion at the firewall) you will have a very slow leak at best. This is mainly because the R-134a molecules are actually smaller than the R-12. They also do not cool as efficiently, so it wont be quite as cold as when your system was filled with R-12. This, theoretically could be remedied with a larger condenser at the radiator, but Im not sure if the newer Mustangs (94-up are R134a Ive heard) will have the fittings in the same place. I have been looking into getting a bigger one, but have yet to really have the money or time to really check it out. Your AC will still be cold, just not REAL cold like I like it... Just thought you might like to know some of this, good luck.
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Cardinal Red '88 GT 5 speed, Cobra Upper/Lower, Dynomax complete Super-Turbo cat-back system, Turbo Coupe Rear 10" discs, 3:73 gears, SN95 Master Cylinder, Summit Racing adjustable proportioning valve, Spec Stage II kevlar clutch, steeda adjustable cable/quadrant, 73mm front calipers, P.A. Performance 130 amp alternator, 99 Contour Electric Dual Fans, Battery relocated, rebuilt 91 T-5, Mass Air conversion
"but remember that unless you buy a new accumulator (black canister portion at the firewall) you will have a very slow leak at best. This is mainly because the R-134a molecules are actually smaller than the R-12." ????????? the only reason you will have a slow leak is due to the o-rings drying out and not sealing properly at the quick connects.
make sure you remove the compressor, accumulator, and line set from car and drain all the oil you can from each. r12 and r134a require different types of oil. compressor and accumulator will have the most, replace all o -rings, gain access to a vaccum pump or take to a shop, charge system back up to 85% of capacity. dont remember the actual charge weight off hand, probably in the 22 to 30 ounce range. if the required charge is 30 ounces only add 25.5. r134a runs at higher pressures than r12 which is why the charge needs to be weighed in correct, if you do everything except pull a vaccum and charge it up, a shop is not gonna charge too much. the price of r134a is sky rocketing so they'll probably hammer you on that, its costing about $10 a pound currently
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1987 Mustang GT Convertible
1985 Mustang Drag Car Project
2007 Mustang GT
Too many mods and parts to list.....
A/C Conversion 
Just thought you might like to know some of this, good luck.
????????? the only reason you will have a slow leak is due to the o-rings drying out and not sealing properly at the quick connects. 
