AC refrigerant question.

if you do it right, there is no problem, but you may be disappointed with the end result depending on how efficient your condenser is. the conversion is fairly easy overall, you have to replace the receiver/dryer, and flush the system thoroughly to eliminate all traces of the oil used in the R12 system. it would be best to also replace the condenser with a more efficient one, replace the compressor with one that is also more efficient such as the sanden 508, and replace the stock hoses with later barrier style hoses. the R134a molecule is smaller than the R12 molecule. the first thing you need to do is take the car to a certified a/c specialist and have them recover the remaining R12, and flush the system. after you have made the needed changes, take the car back and have them draw down the system so that you can add the new refrigerant, or have them do it. DO NOT add refrigerant until the sight glass is clear with the R134a as you WILL run into compressor lock. you need to have a set of R134a gauges if you add the refrigerant yourself.

R134a in a R-12 system is a no-no. R-134a uses a polyester oil, while R-12 uses a mineral oil. If you mix R-134a with mineral oil it will foam your oil and wipe your AC compressor bearings pretty quick. There are some kits that supposedly neutralize the effect. I haven't tried one in a long time, but they used to be junk.

01ragtop said:

R134a in a R-12 system is a no-no. R-134a uses a polyester oil, while R-12 uses a mineral oil. If you mix R-134a with mineral oil it will foam your oil and wipe your AC compressor bearings pretty quick. There are some kits that supposedly neutralize the effect. I haven't tried one in a long time, but they used to be junk.

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Yep, I agree. With that in mind, I'd go to an AC shop or a good auto parts store and get a couple quarts of AC flush and flush the AC system until you can't flush it no mo' Then replace the dryer, inspect all the lines, replace and lube all the o-rings, button it up, put a vacuum on it, and charge 'er up with 134a. You could always replace the lines and/or do a sanden compressor swap too. Really old R12 rated lines can disinegrate when exposed to R134a.

Hey 5.0ina66...... have you considered using duracool refrigerant? check them out at www.duracool.com just a thought...hope it helps

noblesteed said:

Hey 5.0ina66...... have you considered using duracool refrigerant? check them out at www.duracool.com just a thought...hope it helps

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yeah, I use enviro-safe...tree hugger friendly, cheap, easier on the system, cools like R12, and doesn't respond to moisture. As far as I'm concerned, R134 can go f**k itself As long as you don't get one of the cheapo 'replacement' freons with propane or any other stoopid chemicals in it, that's what I'd do if it were mine.

www.icorinternational.com HOTSHOT-been using it as a replacment for R-12 and 134A for years...

r12 alternative

I have used freeze12 and HP38 and have lost compressors in 1 week. I see freon on craigslist every day for $20 per can. I have six in my garage waiting for me to install the "driver Kit" on my 66.

There is pretty-much only two ways to trash a compressor that fast.
1. Incorrect refrigerant charge...TOO MUCH=liquid returning to the compressor breaking valves/pistons, etc.
TOO LITTLE=compressor will not be cooled by the returning gas can smoke the bearings.
2. mismatched system components.

The thing to be careful of is that different refrigerants require different amounts to be "properly charged".

The best way to charge a system regardless of refrigerant that is used is by measuring superheat and subcooling.

But I can tell you that R414 "HOT SHOT" is by far a better refrigerant than 134a, and is a little beter than R12 at moving heat.

valley82 said:

There is pretty-much only two ways to trash a compressor that fast.
1. Incorrect refrigerant charge...TOO MUCH=liquid returning to the compressor breaking valves/pistons, etc.
TOO LITTLE=compressor will not be cooled by the returning gas can smoke the bearings.
2. mismatched system components.

The thing to be careful of is that different refrigerants require different amounts to be "properly charged".

The best way to charge a system regardless of refrigerant that is used is by measuring superheat and subcooling.

But I can tell you that R414 "HOT SHOT" is by far a better refrigerant than 134a, and is a little beter than R12 at moving heat.

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Even a improper charge shouldn't trash a compressor that fast. Too little charge should be safeguarded against by the use of a low pressure cutoff, and I have seen compressors overcharged to the point they freeze over solid and still not have any internal damage. ( not saying its okay to overcharge, because I have also seen pistons split in two because of an overfeeding fault)

Using the wrong oil/refrigerant combo will eat a compressor quick.


EDIT: I should point out that the broken piston I mentioned earlier was not in an automotive application.

I was responding to the post refering to freeze12 smoking a compressor.
134a is the only refrigerant for car ac that will cause you a problem with the wrong oil.
You can use POE or standard oil in R-12,FR12,Hotshot charged systems with out problems.
So that being said, if you trash a compressor and you are not using 134a then you either overcharged or undercharged the system...that assumes that the system was properly evacuated and the system operates normally(all components function corectly).
Overcharging a system (low superheat) will cause liquid refrigerant to mix with the oil washing the bearings causing bearing failure if you way overcharge a system you could cause the compressor to try to compress liquid(refrigerant/oil) resulting in failure.
If ya don't believe me go buy a can of 134a (12oz.) and add it to a new cars ac system then see how long the compressor lasts.

valley82 said:

I was responding to the post refering to freeze12 smoking a compressor.
134a is the only refrigerant for car ac that will cause you a problem with the wrong oil.
You can use POE or standard oil in R-12,FR12,Hotshot charged systems with out problems.
So that being said, if you trash a compressor and you are not using 134a then you either overcharged or undercharged the system...that assumes that the system was properly evacuated and the system operates normally(all components function corectly).
Overcharging a system (low superheat) will cause liquid refrigerant to mix with the oil washing the bearings causing bearing failure if you way overcharge a system you could cause the compressor to try to compress liquid(refrigerant/oil) resulting in failure.
If ya don't believe me go buy a can of 134a (12oz.) and add it to a new cars ac system then see how long the compressor lasts.

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I understand what you meant, but if the system is working properly a short charge won't hurt the compressor because it has a low pressure "safety" cut-out. An overcharge will take down a compressor given time, but I have seen them freeze up with no internal damage. I also mentioned that I have seen some bad things happen when overfeeding/overcharge is not rectified. SO, on the overcharge we are in agreement. As for refrigerant/oil combos take a look at this. The first row of samples show what some of this "drop in" stuff will do to mineral oil. Now you know why the Freeze 12 took out the compressor so fast.

Bottom line is this: There is no true drop in replacement for R-12. Even the r414b (hotshot) runs with a short charge. That is not to say it won't work, but if you have ever seen a system with a liquid line sight glass and R-414b it will have bubbles, and that means refrigerant is flashing before the metering device. In a low temp application this is more prevalent, and usually the solution is to adjust the TXV, or change the metering device if it is not adjustable. ICOR international will tell you just to charge the system to 80 percent, but IMHO that is marketing hype. It would be hard to sell their refrigerant as a "drop in" replacement for r-12 if they had to have an asterisk explaining that little fact.

Bottom line: if your looking for a cheap replacement for r-12, Hotshot will work in a car AC. Just keep in mind the link above.

More to the topic, however, is the evap and condenser in the OP's car. If they have not been sealed from the elements since your dad pulled the AC out, I'm not sure I would use them at all. That's just me though.

EDIT: So no one is mislead: The website that I posted the link to regarding the oil Miscibility is owned by Autofrost or R406a. While the samples are real what they fail to mention on that page is that r406a will eventually break down mineral oil and become very discolored. It is recommended that you use a AB( Alkyl Benzene) refrigerant oil with either r406a or r414b, but now we are right back to square one with the r134a issue. So considering the fact that the oils at least should be changed, R134a is the better choice because it is not a blend of refrigerants like the R12 replacements. The blended replacements can frationalize and the different refrigerants will leak at different rates. In the case of Autofrost(r406a), it can leave you with a flammable substance.

There is a reason EVERY major auto manufacturer uses R134a

As for Duracool: http://www.epa.gov/Ozone/snap/refrigerants/hc-12a.html

In summary point number 4 from the above link:

May hydrocarbon refrigerants be used to replace CFC-12, commonly referred to as "Freon® ," in cars?

No. It is illegal to use hydrocarbon refrigerants like HC-12a® and DURACOOL 12a® as substitutes for CFC-12 in automobile or truck air conditioning under any circumstances.

Party on wane...use what ever makes you get that warm and fuzzy feeling!!!
But for a novice I would strongly sugest R-12 or Hotshot...and if you're worried about the oil getting "darker" switch it to POE?!?
But the big three auto manufacturers tried just changing the oil to POE and running 134a in R12 systems in the early 90's and if you owned a 90-93ford/chevy/dodge and lived in arizona in the summer you already know that the a/c would not keep up at temps above 100degrees F. reason...R-134a does not tranfer heat as well as R-12 and that is not an opinion that is fact.

valley82 said:

Party on wane...use what ever makes you get that warm and fuzzy feeling!!!
But for a novice I would strongly sugest R-12 or Hotshot...and if you're worried about the oil getting "darker" switch it to POE?!?.

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"darker" due to acidic breakdown of the oil, and if your have to change oil it is not a "drop in" replacement.

valley82 said:

But the big three auto manufacturers tried just changing the oil to POE and running 134a in R12 systems in the early 90's and if you owned a 90-93ford/chevy/dodge and lived in arizona in the summer you already know that the a/c would not keep up at temps above 100degrees F. reason...R-134a does not transfer heat as well as R-12 and that is not an opinion that is fact.

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No doubt about it, in an automotive application r-134a in a R-12 system is not as efficient as the old R-12 was. It transfers heat fine in a system that was designed to use R-134a. The reason it doesn't work as well in a R-12 system is, -as someone already mentioned- physical molecular size of R-134a is bigger than R-12. And the PT relationship is moved up the scale.

There really is no "drop in' replacement for R-12, this has been my point all along. There are some usable alternatives, but each has its own issue that has to be solved. If the compressor is already old or parts are old then just use the Hotshot or autofrost. but if using new parts or installing a system that was designed for R-12, then change the oil and use the correct refrigerant with that oil. If you don't like R134a, fine just make sure you use the right oil for the Hotshot or what ever you use.