I moved from Michigan to Phoenix Arizona, (The Land of Dry Poop and Dry Boogers) last year, and here is what I have found concerning the myths of converting from R12 to R134a refrigerant.

Converting to 134a is desirable considering the costs of genuine r12. It is also desirable because r12, at close to $1000.00 a 30 lb. can is being smuggled in from Mexico. The fear is that you may end up buying propane(which works as a refrigerant) and introduce a flammable gas into your underhood system. I won't buy that crap, based on the fear of being shown the pictures of what happened.

R12 and R134a both produce the same ultimate results of temperature transfer, but R134a has a lesser efficiency. In automobiles it would be desirable to increase the evaporator and condenser size to accomodate this ineffeciency, but in many cases that cannot be done. In most cases the differance is not noticable.
 Myths have been created concerning compatibility of the oil used to irrigate the compressor. In 134a Ester 100 is used, and to convert, I would recommend using this oil, even in the presence of old, R12 oil, which is best vacuumed out. They do get along.( If you mix brake fluid and motor oil you get dramatic results within hours. Seals designed for these two fluids are not compatible.)
 To convert is very simple. I'm a big fan of Carquest, go to Carquest. Buy a conversion kit. Screw on the adapters for the A/C guage port fittings. R134a is different. Do not change any O-rings. This is where I will get the heat from the Theorists. Your O-rings will not leak, nor will your compressor be destroyed by the change in refrigerant.
  Frankly, Guys, I don't need you. You are not my customer base. Nor do I EVER lie to a customer. I make a lot of money on this shit fast here in Veenicks baby! But I never sell the old refrig. Its a waste of your money, and its a polluter. Can you convert your 68 Camaro? Yes. We are doing a 68 Chevelle Big Block with an aftermarket "perfect" conversion" this week, but that is a conversion from a faboo '60's car that never had A/C. I'm not advertising. I just want you to realize that you can get your A/C up and working again without paying for R/12. In the old days you could get 12 OZ cans of R12 and shoot up the old systems every summer. Those days are back. R134a goes for $7.00 a 12 OZ can, and even if you have a leaking system, you can shoot up with a can tap after you convert.

To do a conversion right you must replace the condensor and the evaporator.  Any thing else is just a crappy job IMHO.  There are no quick and easy fixes.  R134a operates at a different pressure range IIRC.

Sgtar15

I can get 12 oz cans of R12 for $35. Down where you are close to MX you must be able to get them for cheap. Can't you just drive over the boarder and buy it legally anyway ?

i converted mine (84 chevy truck) almost three years ago. i put a new dryer and re-man compressor on it, oil charge and 3lbs of 134 and today it will still freeze you out! i was told by auto zone that it is illegal to convert r12 guages/manifold to r134 fittings and no one makes a conversion for that so i just borrowed one from a friend
good luck!

Yes you can but you cannot legally bring them back to the US.  Just charge up your system in the parking lot at the store.

Can't you sneek it over the boarder in the cans or do you have to charge it up in Mexico ?

Sure you can sneak it over and they might just confiscate it if you are caught OR they might decide to arrest you for smuggling a contraband.  It just depends on the quantity you are attemping to bring back.

grimshaw,

I've had a lot of experience with this.  I used to be a professional mechanic, and spent 4 years building custom cars and hot rods.  I dumped the auto profession, and became a computer prfessional, PAYS MUCH BETTER!!!

Any how, get this!!!!

1) The auto profession is full of mostly crooks and liars.  They will tell you ANYTHING and sell you things that you do not need in order to make a buck.

NO OFFENSE INTENDED TO ANY AUTO TECH's!!!!
I know some killer mechanics that are great guys, but ask them what they think of the profession in general, if you do not believe me!!!

2) You DO NOT HAVE TO REPLACE ANYTHING IN ORDER TO CONVERT TO R134.  The whole line of replace this and that is a line of crap to get you to buy a bunch of parts you do not need!!!!!!

I have personally changed the refrigerant in 5 cars, and never changed 1 part to do it.

All I did was dump the oil out of the compressor add the oil and valves, and vaccuum it down and charge it up with R134A.  One of the cars that I did this with was my sh%$t box 86 Chrysler LaBaron.  I drove the car for 3 years and 45K miles after and never had a problem out of the AC.

The Tech.'s at a local shop we used to deal with were bringing in their old cars, sucking out the R12 into the recovery system, charging it up with R134A, and reselling the R12 to customers.  They also NEVER had any problems with their AC systems, and NEVER EVEN REPLACED THE OIL!!!!!!!!!!!!!

Don't listen to any one that tells you otherwise, they either do not know, or they are telling you something in order to sell you parts you do not need.

By the adapter kit, if you want change the oil, suck 'er down, and charge her up, good to go!!!!

DON"T WAIST YOUR MONEY!!!!!!!!!!!!

starsil9

409A completely compatible with R12 but illegal to mix, say the evowacko's

Right Starsil (! You really don't need to evacuate the oil either! One of the most stubborn systems is the old full-size Chevy( band-aid, not bow-tie) Suburban with the dual air. I've converted a dozen of those, and they have more o-rings than you could ever replace. Never had a problem with that, although the the Chevy R4 compressor is a tird. In that system there is at least 40 feet of hose, and you cannot suck all the oil oil out of that system no matter how long you crank the vacuum. I've left that system on under superstition quite a bit longer (overnite), charged it up, and fukna! Its cold! But there is R12 oil in there. My customers are the type that come back and complain. If I get 1000 freaks at my door, I'll be sure to remind you to change every o-ring! Its 97 today. We on a holiday every day here in the "Valley of the Gun".

And I have a case of R-12 I have no use for.  Both vehicles use R-134.

marsh

Marsh, I am not in the business of profiteering, but the r12 you speak of may more valuable than you ever dreamed of. Consider a Shelby Cobra owner as a potential buyer, and get on the Internet.Freak out if you have real R12! because of guys like Jay Leno that believe the only true path is R12. A strange fitting? Not! Not on my Cobra! I have 7 shooter cans, and I feel like I can make 1  true 60's hotrod happen.

grimshaw,

It's great to see a Tech that is doing honest work, you might agree that it's rare!!

Any how, I missed Jay Leno's comment about R12, I work nights and don't get a lot of time to watch late night TV anymore.

What did he say?  

I know he owns an extensive car collection, but I seriously doubt that ole' "big Jaw" works on his own stuff!!!!

Oh, yeah, the only difference I noticed between R134A & R12 is that it takes a little longer for the air blowing out to get as cold as R12.  Other than that, cold is cold.