Changing A/C back to R12 from 134A on my 71

[Gene]

What do I need to do? Do I need another drier or can I use the one already on it? Its not that old I put a new one on when I made the conversion to 134A. The thing is it just dont get cold enough now that I changed it over and I wanna go back to original.

[Old Chevy]

Gene,
You should replace the receiver dryer, and you must purge all of the R134 oil from the pump. Ideally, you should purge the entire system. The oils in the r134 are incompatible with R12 oil.

Cheers

Richard

[sam's 72]

Why doesn't the 134a work good in these trucks? This is not the first time I have seen some one switch back over to R-12. I was thinking about going to R-134a, but I don't think i am going to do this. I will put the newer style kit on it though.
Sam

[Gene]

I should have mentioned that I will be putting a new compressor on it since my old one locked up. So I should be ok on the oil issue Richard?

I dunno why the 134A dosent work well in our trucks, all I know is that my air got a good 10 degrees cooler before I made the switch. You say you are goint to the new style? You mean the newer compressor? What is needed to make the change?

[sam's 72]

There is a kit out there, that does away with thge POA valve and the exspansion valve, moves the dryer up to the fire wall, it has pressure switches on it and take a orfice tube, like on a newer model. then you dont have to wory about the POA vavle sticking any more, still uses R-12.
Sam

[Blue68]

As I understand it, r134 is not as effecient a coolant as r12, thus a system not designed for r134 will not work as well as it did with r12. I think you need a larger condenser with r134 to acheive same results in an application as r12.

[HvyChevy454]

as said, R134 is not as efficient as R12 but it is cheaper and works to an extent. The reason it does not work well n older vehicles is that are older vehicles do not have a "max" air setting just a hi setting. The max air setting in new cars gets the pump a spinning making the r134 seem just as good as r12 in a hi setting

[Hugger]

I have the same problem;
Spent over a grand for the conversion, and it does not coll well.
When the compressor is on, the air gets pretty cool, but they can not seem to get the pressure low enough to keep the compressor on.
Now they tell me I need a new compressor...
What does the "Max" setting on the newer A/C systems do?

[tom hand]

The main reason r-134 does not work well in these trucks is the condenser is really too small for r-12. Look at a 73 up truck and see how much bigger they made it. The max setting on newer vehicles just recirculates air so it is cooling air that is already been cooled. If you air system is working properly ours will do that too...thats what the vacuum operated vent door is for

[O'l Buck]

I've never changed a passenger vehicle over, but we've changed several semi trucks from r-12 to r-134A and always had the problem of it not cooling as well. A freind of mine was telling me the other day that there is an additive available that will boost the efficiency of the 134A. I can't remember right now what it is called, but I've seen it at wal-mart. It's in a little can like the a/c oil is in. He says it works very well with this additive.

[2wdBlazer]

Check out http://www.refrigerantsales.com/ . Go to products on the left and check out AutoFrost for R-12 systems and CoolTop for R-134A systems. I have used both and they are awesome. They actually reduce the air temps.

[StingRay]

Gee I have two of my 83 Toyota's retro'd to 134 and they both cool every bit as good as they ever did with R12. My buddy has a rad shop and does this conversion all of time with great success. Depending wich oil you use the 134 oil can be compatible you just have to use the right one. All O-rings must be changed over for the conversion to work. I have heard of a few people that have had corrosion problems due to incompatability of the r12, r134a and some the their respective oils but it is very rare. One of my Toytoa's has a super tiny leak on one of the compressor seals but it takes about two years to leak down and is virtually undetecable when tested. This as I understand is simply because the 134 has such tiny molecules.

[Chevy Wrench]

I dont see what the problem is with 134a. I've personaly done close to 100 conversions. Not one has come back because it wasnt cooling enough. If the conversion is done right, you will not have any problems. Just make sure that you are putting the right oil in the system, flush the ENTIRE system, and charge to about 90 percent capacity. Also, when you do charge the oil, make sure you are using oil that hasnt sat around for awhile. Ester and p.a.g. collect moisture quickly, even trough the plastic bottles!! And moisture is your a/c systems' worst enemy. And dont go off of the pressure readings, rather go off of temp. readings. Good luck with your conversions.

[OLDCHEV4X4]

If i could find R-12, i would use it. But the stuff isn't available any more.
Randy

[Glen]

134 requires a more efficient condenser than your r-12 setup, investing in a nice condenser would probably be the same price and less hassle than converting back to r12

[lofly'a]

hey "chevy wrench", what do you use to flush the system and what method? i know there is special equipment to do the job, but can the average joe do it, and how? i have converted a few, and we've always used isopropyl alcohol with good results, but i have seen failures (usually compressor lock-up within a year).

[70shortnphat]

Ill be working on my a/c in a couple off months and plan on using a condenser out of a newer suburban (one with front and rear air)
They are very large but should fit in our trucks just fine.

[Longhorn Man]

Anyone tried that "freexe-12" ? Any luck? I just heard of it the other day and thought I'd ask.

[oldyeller]

You can still get R12, but its pricey and you have to have a license to buy it...

[68 Suburban]

I have a 30 lbs container of virgin R-12 with about 24 lbs still remaining in it. If I can sell it to anyone legally I am willing to let it go

[Roberty]

Originally posted by Hugger
I have the same problem;
Spent over a grand for the conversion, and it does not cool well.
When the compressor is on, the air gets pretty cool, but they can not seem to get the pressure low enough to keep the compressor on.
COLOR=red]Now they tell me I need a new compressor[/COLOR]...
What does the "Max" setting on the newer A/C systems do?

You mean they charged you a grand for the conversion and they didn't even replace the compressor?
I changed a 85 Silverado over that I owned about three years ago to the new 134a freon - did it myself except for charging the system back up. I replaced the compressor, accumulator, orfice tube and bought the conversion fittings kit. Cost me about $200 total including having it recharged. It took slightly longer to cool it down when first getting in the truck but it seemed to cool just as good after getting it cooled down. This is an easy conversion to do yourself.
Robert

[Chevy Wrench]

To flush the system, I use a product from Castrol. It is called, I beleive A/C Flush. No special tools except a flush gun that is used with shop air. You do need to replace the receiver/ drier and the compressor. If you havent "launched" your compressor, you can still use your old condenser. If you have any mechanical skills, this conversion should take 3 to 4 hours, depending on what you have to replace. Just take your time, make sure there is no old oil in the system and replace all of your old o-rings. No special methoods, except flush and back flush eveything. Good luck, and if you have any more questions, feel free to ask.
John
The Freeze 12 is pretty good, it is propane based. We use a product called Enviro Safe. Still propane based, but in my opinion, it cools better. R-12 is very pricey, $900.00 for a 30lb can compared to about $80 for R134a. Mind you, these prices are based on my cost, retail would be about 30 percent higher.

[wHATANERD]

the compressor does not need to be changed out to make the conversion, They make a synthetic oil for 134a that will blend with oil residue left over from r12, I'm using the same compressor and it works find.

[Bowed]

Originally posted by 68 Suburban
I have a 30 lbs container of virgin R-12 with about 24 lbs still remaining in it. If I can sell it to anyone legally I am willing to let it go

I was in econo-lube today and they told me they are getting $90.00 a pound for R12 . Now lets see , your 24 pounds times $90 thats a retail of $2160.00 . Better not sell it to cheap

[Chevy Wrench]

The problems with synthetic oils are:
1. Synthetics are a great vehicle for the transfer of moisture.
Moisture introduced into the system will kill a compressor in less than 30 minutes. If you are not VERY careful, you WILL introduce mosture. And you WILL launch your compressor. You can bank on that.
2. Synthetics do not disipate heat as well as other oils. Insted, synths. tend to capture heat and store it, thus adding even more heat into an already hot environment.
If it were my money, I would replace the compressor. Because I wouldnt want to pay for 2 of them.
I have been working in this feild for the past 13 years, and have hundreds of hours of school just on the subject of automotive A/C. It is what I do for a living, and the living is good.
John