R134a conversion question

["Turbo-T"]

After reading this:

AC 134a Retrofit

I am aware that R134a in an R12 system is not efficent as R12.

I am wondering if there's a such thing as a more efficient condensor? Would that help increase cooling of R134a in an R12 system? Does anyone make a more efficient aftermarket condensor?

Also I may decide to run a front mount intercooler in the future. Will this pose any issues in the condensor in the stock location?

 

[LBNJWE4]

I just saw a GN get 40* out of his vents with r134a. Shouldn't be a problem.

 

[Black Car]

Instead of converting, use freeze 12. Works great with the old system. I started using freeze 12 over 7 years ago and have used it on the last 3 of my Buicks.
Use to be $7/can years ago.

Gary

 

["Turbo-T"]

Where can I get this Freeze 12?

Also where can i get a vacuum pump to draw the moisture out prior to charging?

 

[BetMinesFaster]

Just drive it up here to Minnesota and you can use my ac machine!

 

[charlief1]

Yes, there are high efficiency condensors available. Freeze 12 is a blend and doesn't properly distribute the oil in the system and isn't recomended by any of the people that make compressors. I tried it myself and fried a compressor. Check my other posts to see answers on conversions. I do this for a living if your'e wondering.

 

[LBNJWE4]

Anyone use Enviro-safe? I bought two cans but haven't used them yet. Supposed to be able to use it with either r12 or r134!

 

[Louie L.]

In the early days i did a 134a conversion on the GN and it did not cool well. My buddy just did my TTA with 134 with a new compressor. It is cold! I havent checked the temps, but it was nice.

 

[toofastforyou]

Last year, I did convert my GN to r-134. To do it properly, the key here is to replace the accumulator dryer as it contains some oil meant for r-12 which is not compatible with r-134. After replacing the accumulator, we put in 5 oz. of "Ester 100" oil, then filled the system with r-134 (43 oz.). It's been working great ever since! :wink:

Claude

 

["Turbo-T"]

Is it required to flush out the system? And what do you prefer to use for leak detection?

Someone did put on the R134a fittings but I don't know if they did the conversion right or not.

I do know the system currently does not work. I would venture to say there's a leak in it.

 

[JST A 6]

Nobody's mentioned it yet, but I'd get a 134a orifice tube for it too. Most people that are not in the A/C business would not think/know to change it, but it will have a dramatic effect on how well the system cools for you. From what people on here have said, the orifice tube for a '90s Ford F150 fits and works great. Shouldn't cost you much at a Ford dealership (except your dignity if someone you know sees you coming or going from there:biggrin: ).

Next I'd go to the Buick dealer and get all new A/C lines and seals, or I think Gbodyparts has them too. The seals and the rubber hoses (where the metal lines crimp to them) are the most common culprits when you have leaks.

I have my own vacuum pump but that's because I work in the HVAC field (mainly residential & commercial systems but I've worked on automotive systems too). I'm not sure what they can be picked up for but I know mine was over $400--too much to spend if you're only likely to use it once or twice. If I were in your shoes I'd probably just take it somewhere to get the system evacuated & charged.

 

[Jerryl]

Here is another thread on the conversion.
http://www.turbobuick.com/forums/general-turbo-buick-tech/192567-r12-r134-convertion-need-help.html

 

[zues1]

a/c conversion

the way weve done conversions in our shop is change dryer & orfice tube i have always use (white gm) pickup any part store cant say differance in (blue,orangeor red)ford orfice, flush system can buy kit at part store use with shop air dont use straight shop air because of water in air lines drain oil out of compressor put about 8oz ester oil in whole system, r12&r134a oil are not compatable recharge with about 2lb 134a change all orings( not compatablewithr12)this is how weve done it since 93 when freon changed, oh i have freon detector says freeze 12 is propane? best way to find leak with 134a is with dye unless so bad wont hold vacum most leak detectors will not detect r134a my 2cents,mike

 

[49-blues]

An easy fix is to find your low pressure cutoff switch on the accumulator remove the wire and rubber cap on the switch , in between the two prongs you will see a screw- just turn it alittle to the left to lower the kick in pressure- monitor your adjustments with a temp gauge in your air vents. it will get just as cold as R-12-i have mine set at 33*.

 

[charlief1]

Ok ya'll, lets set a few things strait. R-12 is difloradicloramethane, R-134 is tetrafloraethane, Freeze 12 is a blend of R-502, R-134, R-22, and R-12. The majority of the mix is R-134. It will allow your system to work but because it won't allow the oil to distribute properly it will eventually kill your compressor. I have no idea whats in "envirosafe" but I do remember when the first "safe" alternatives were out there and they were mostly propane and if you found a leak you could have a reaction. I blew an accumulator up while sniffing a system. If you don't know what's in it don't use it. The oriface tube is nothing more than a restriction in the system to allow the expantion of the liquid refridgerant into a gas. Think of a spray can. When you spray a liquid out of a can the can body drops in temp. Same thing for an A/C system. The faster the liquid changes to a gas the higher rate of temp drop. By changing the oriface tube to one with a larger hole in it the faster and higher the temp drop will be. GM was the first to use the CCOT system and Ford followed. But to avoid patent fights Ford used a tube with two holes in it which allows for a higher rate of change so most ford evaporators are smaller than Gm. By changing to a ford blue or red oriface tube you gain a higher rate of change and drop temp better. GM white has one hole that's .052 in diameter. Ford blue has two holes that are .067 and the red is .062 in diameter. Pag is a better alternative oil than ester and will hold up better. It also comes in different viscosities so you can get the best one for your system.

 

[aminga]

If you change from R-12 to R-134a you will need to change the orifice tube AND the dryer. Since the dryer can hold oil the oils are not compatible get rid of all the places the old ester oil can hide.

Basic procedure is to remove the last reminants of R-12 from the system. Get a shop to recover it because it is valuable.

Remove the receiver dryer and orfice tube

Flush the system with A/C system flush. Get the condenser and evaporator good.

Reinstall the new orifice tube and new dryer and put new R-134 compatible o-rings

Draw the system into vacuum for at least 30 minutes and make sure that it will hold that vacuum so it won't leak.

Charge it by the gauges. For get about the 85% of a R-12 charge or whatever the "common wisdom is" Look up the PT chart for R-134a (based on temperature at the condenser and charge until you hit those high side and low side pressures. or until you get the outlet temp you want.

I did mine a couple of years ago so I took the time to experiment with some of these "common wisdom" things with R-134a. At an 85% charge the pressures were very R-12 like and not enough to get into R-134's sweet spot. Outlet temp at 85% charge was 65 degrees.

Charged to the proper pressures for the temp outlet discharge was 45 degrees I wound up putting almost a full R-12 charge in the system.

R-134 can and does work you just have to charge it by the Numbers.

 

[SloGN]

Ok ya'll, lets set a few things strait. R-12 is difloradicloramethane, R-134 is tetrafloraethane, Freeze 12 is a blend of R-502, R-134, R-22, and R-12. The majority of the mix is R-134. It will allow your system to work but because it won't allow the oil to distribute properly it will eventually kill your compressor. I have no idea whats in "envirosafe" but I do remember when the first "safe" alternatives were out there and they were mostly propane and if you found a leak you could have a reaction. I blew an accumulator up while sniffing a system. If you don't know what's in it don't use it. The oriface tube is nothing more than a restriction in the system to allow the expantion of the liquid refridgerant into a gas. Think of a spray can. When you spray a liquid out of a can the can body drops in temp. Same thing for an A/C system. The faster the liquid changes to a gas the higher rate of temp drop. By changing the oriface tube to one with a larger hole in it the faster and higher the temp drop will be. GM was the first to use the CCOT system and Ford followed. But to avoid patent fights Ford used a tube with two holes in it which allows for a higher rate of change so most ford evaporators are smaller than Gm. By changing to a ford blue or red oriface tube you gain a higher rate of change and drop temp better. GM white has one hole that's .052 in diameter. Ford blue has two holes that are .067 and the red is .062 in diameter. Pag is a better alternative oil than ester and will hold up better. It also comes in different viscosities so you can get the best one for your system.

I'm getting ready to redo my a/c system by replacing the compressor and the dryer and the orafice tube. I guess i will be going back with 134A this time instaed of using the freeze 12 stuff. My car has stopped up the orafice tube twice so i think the compressor is shot. I have been keeping it going the past couple of yrs with a can each yr as it leaks out over the non a/c weather months.

also what part # for the ford tube should i get. before the thing stopped up my car would make 38-39 degree cold air on a 90 degree day so i like my air to be cold.

 

[charlief1]

If you change from R-12 to R-134a you will need to change the orifice tube AND the dryer. Since the dryer can hold oil the oils are not compatible get rid of all the places the old ester oil can hide.

Basic procedure is to remove the last reminants of R-12 from the system. Get a shop to recover it because it is valuable.

Remove the receiver dryer and orfice tube

Flush the system with A/C system flush. Get the condenser and evaporator good.

Reinstall the new orifice tube and new dryer and put new R-134 compatible o-rings

Draw the system into vacuum for at least 30 minutes and make sure that it will hold that vacuum so it won't leak.

Charge it by the gauges. For get about the 85% of a R-12 charge or whatever the "common wisdom is" Look up the PT chart for R-134a (based on temperature at the condenser and charge until you hit those high side and low side pressures. or until you get the outlet temp you want.

I did mine a couple of years ago so I took the time to experiment with some of these "common wisdom" things with R-134a. At an 85% charge the pressures were very R-12 like and not enough to get into R-134's sweet spot. Outlet temp at 85% charge was 65 degrees.

Charged to the proper pressures for the temp outlet discharge was 45 degrees I wound up putting almost a full R-12 charge in the system.

R-134 can and does work you just have to charge it by the Numbers.

Well I'm glad to see someone hasn't done the usual and figured out some of the "magic" of refridgerant. If you really want a correct charge of R-134 then the trick is to have a pyrometer. The difference in temp between inlet and outlet of the condensor should be right around 30 degrees and the difference between the inlet and outlet temp of the evaporator should be minimal. No more than 10 degrees. The lower the temp difference of the evap the beter. It works at best efficiency this way. A minimum of 30 miniutes under vacuam is required but the longer the better. At the shop we do 2 hours but if you have the equiptment then hook it up overnight and let it do it's job. If you have a suction pump with enough umph then you will see "smoke" coming out of the pump. It's the moisture coming out of the system. The more removed the better. As far as the orifice tube about a 95 ford pick-up should do it. You should get it to at least the same temp as R-12 but you might be able to get it lower. Also remember that because R-134 isn't as efficent as R-12 you will have to be moving to get the best results. The more air moving across the condensor the better. We usually install the oil after sucking it down the system but if you don't have an oil injector then remember, 2 oz to the accumulator, 6 oz to the compressor, and 4 to 6 oz in the condensor. Rotate the compressor to clear the oil out of it before you charge it and under vacuam. CLEAN EVERYTHING!!! If there's any trash in the system it will screw up the compressor or plug the orifice. Replace ALL of the o rings but check the hoses very carefully. If you have any doubts about the rubber hoses then replace then. The original hoses aren't as well made as the newer hoses and will leak through the rubber sooner or later. Add a UV dye to the oil so you or a shop can see if there's a leak.

 

[zues1]

what kind of pressure readings are you having with 14oz of oil in a 8oz system i always run into crazy pressure readings with that much oil not enough room for freon?

 

[charlief1]

what kind of pressure readings are you having with 14oz of oil in a 8oz system i always run into crazy pressure readings with that much oil not enough room for freon?

What type of gauges are you using? We have two recycle/charging stations and alternate them once a week. One is used for recovery and one is used for charging. After the weekend we change so that the air seperates from the R-134 after 48 hrs. Then we purge the one we're using for the week for charging. The presures run a little higher than usual, About 55psi on low and 250-275 high but we haven't had any come backs since we started using temp to charge the systems. If you get mitchel on demand you can look up vehicles from 83 up but there is an extra charge for pre 83 cars. It gives you capacities, specs, ect but since they changed their search engine to google it's a pain.