well boys and girls i live in las vegas nevada the hottest place on the planet and i am the king of a/c..i have seen it all ..let me tell you some things about ac.,let me start saying retrofitting is crap ..why would any sane human being wana take a cold ac system and put 134a in it..?? money $$$$$ they say it would cost 60.00 a pound for genuine r12 freon right?...ok lets look at what you would have to do to retrofit a 1988 chevy truck from r12 to 134A...lets start off with a sceniro ..guys pulls up to the parts store with a truck that the air quit working, the shop told him the pump was no good and they recommend a retrofit and a pump 800.00 whole job the guy says no way im going to do it myself...first of all lets look at what is needed to retrofit properly ..you need a new dryer and a orfice tube ..dryer 45.00 orfice tube 5.00 you need to COMPLETELY flush the ac system ...got it so far ..gallon of flush 20.00 ..and change the any hoses to green stripe gates hoses...and a pump because the guys compressor is shot leaking out the front pump seal ....always buy a new pump ..rebuilt /reman are junk ive gon through 5 pumps before i got a good 1...lets look at the down side to retrofiiting r12 is a very good gas as far as cooling propertys same as propane ,,you could put propane in a ac system and it would work fine ...just exposive problem,.134a needs a extra fan in the front to help bring the heat out of the truck because the 134a is a hotter gas ..also it is less permeable gas smaller molecules it goes right throught he regular r12 hoses //when a vehicle is retrofiited PROPERLY there are few problems ..the biggest reason normal joes retrofit is money and they can still buy the 134a at parts store with no license..lets wrap things up here ...there are 10 aftermarket gases out there on the market for replacing r12 ..one of my favorites is hotshot 414b ..it does 2 things it is 12 % colder than R12 and is 32%colder than 134A ..and it uses only 80% of the charge for a system ..so if your truck holds only 3 lbs you only fill 80% ...some shops say that hotshot ruins hoses and seals but i have used it for 3 years now and not 1 failure..also when you get a guy that messes up his ac sysytem on a r12 to 134 conversion i can use it in both systems..no oil change needed ..thats the deal with 134a and r12 2 diffrent oils and CAN NOT have both oils in the ac system at once .it wont explode just 1 gas uses 1 type of oils only ..if you use 134 oil in a r12 gas it wont cicrculate through the system imeediate pump failure ..so why would anyone want to take a r12 system and put 134a in it , the complaint is always the same ...it lasted about 2 days and quit ,,,,because the shop did not change the hoses or seals and the gas leaked out ,the shop took them for a ride and it cost the poor guy 200.00 the shop just fixed the large leak at teh fitting recharge with 134a see the rip off here..now lets say the shop is a good shop right? they would tellt he customer that would retrofit the truck or car and give them the info like "sir we will have the system flushed , the dryer and orifice tube changed and will place a federal sticker stating the retrofit , bit when you get to a stoplight it might raise the vent temputaredone be alarmed it what is called flashgassing wich is the high side not getting enough airflow over the radiator ,,to fix this you will need a electric fan installed on the front .....
on my personall truck i have a 98 chevy fullsize trucj with a v8 ..i took the 134a out and installed hotshot ,remember hot shot is 30% colder then 134a ..my truck DOES NOT heta up at the stop light and blows so cold i have to turn the heater knob up....its been in for 2 years no problem...and also keep in mind the compressor is the heart of a ac system ...134a installed in a older model makes more head pressure then r12 that is harder on the compressor more heat ..r12 does a max of 245 on the high side 134a can goto 350 psi !!! well i guess the answer is get info and research..you can goto to hotshots website at
www.hotshot.com later randy...stay away from freeze 12 it is junk ...all it is 134a with some butane mixed ....ask for hotshot or FR 12 at your local shop..