FR-12 vs. R-12
05-07-2008, 04:48 PM
#46
Race Car
I wasn't looking for a few degrees of cooling, though it's an added benefit of R-12. I wanted instant gratification. Sometimes I'm willing to pay someone to help me, esp. if it's something I don't want to do... or don't have the time to do it.
And you know an R-12 conversion to R-134 costs more than $5.80
Let's see, evap, receiver/drier, fittings, high-pressure hoses, might as well rebuild the compressor, freon, charge equipment... labor.
And you know an R-12 conversion to R-134 costs more than $5.80
Let's see, evap, receiver/drier, fittings, high-pressure hoses, might as well rebuild the compressor, freon, charge equipment... labor.
Dan
'91 928GT S/C
05-07-2008, 05:10 PM
#47
Rennlist Member
No, that's not true. You don't need to replace the evaporator or condenser when converting, you only need to flush them with mineral spirits, then blow it out with compressed air ($5?). All the o-rings in the system are cheap, new drier $40, fittings? You can get hoses rebuilt for ~$50 at a shop that has a crimper. Also, you don't need to rebuild the compressor. Again, many people have kept the same stock hoses and left the compressor alone, only draining the oil from it (especially with the convenient 6E171 drain plug). In fact, my former '86 ran fine for two years (when I sold it) with the non-barrier original high-pressure hose. A bottle of ester oil, $10 max? So it just comes down to the labor in replacing the o-rings, I don't put a price on that because pretty much any DIY wrencher can do this. Oh, and you would have to borrow someone's vacuum pump, those are around $200 to purchase.
Dan
'91 928GT S/C
Dan
'91 928GT S/C
I'm not arguing this is a relatively simple job for the DIY'r. I'm just asking that you don't over-simplify it because it's not that easy or that cheap ($5.80)
05-07-2008, 06:14 PM
#48
Administrator - "Tyson"
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Okay, so now you talking over $100 to DIY. To include hunting down a vacuum pump, running down to the hose crimp store, etc.
I'm not arguing this is a relatively simple job for the DIY'r. I'm just asking that you don't over-simplify it because it's not that easy or that cheap ($5.80)
I'm not arguing this is a relatively simple job for the DIY'r. I'm just asking that you don't over-simplify it because it's not that easy or that cheap ($5.80)
A timing belt job is a relatively simple job as well. Just buy a belt, few rollers & replace everything.
05-07-2008, 07:20 PM
#49
Chronic Tool Dropper
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Okay, so now you talking over $100 to DIY. To include hunting down a vacuum pump, running down to the hose crimp store, etc.
I'm not arguing this is a relatively simple job for the DIY'r. I'm just asking that you don't over-simplify it because it's not that easy or that cheap ($5.80)
I'm not arguing this is a relatively simple job for the DIY'r. I'm just asking that you don't over-simplify it because it's not that easy or that cheap ($5.80)
If, for some insane reason, you decide you really just want to "top off" the R12 and suffer with the leaks and refrigerant loss, then you can't use any of the blended refrigerants. You MUST use R12. The blended refrigerants are subject to fractionation, where the smaller molecules escape first through the holes. There's no free lunch here, and $5.80 is close enough to free to remind you that it isn't a real solution.
-- Fixing the leaks costs the same no matter what refrigerant you choose to refill with. New o-rings and labor.
-- Once the system is opened to atmosphere, like while while you are fixing the leaks, you'll need a new drier. You'll need to add oil for the stuff lost in the old drier, no matter what refrigerant you choose to refill with.
-- You'll have the compressor out to replace the o-rings at the hose connections and at the manifold plates. It's pretty darn easy to drain the old oil out, flush with new oil a couple times, then refill with the new oil. If you choose polyolester oil, you can charge with any refrigerant.
-- You'll have the expansion valve out to replace the o-rings at the hose connections and evaporator side fittings. Labor and parts are the same no matter what refrigerant you choose to refill with. A brand new R-134a-rated expansion valve is less than $30 last time I looked.
-- You'll need to vacuum the system completely before recharging, no matter what refrigerant you choose to refill with. If you decide to charge with R12 or R-134a, you can take the car to a real commercial AC shop for the evacuation, leak-check and charging. Can't do that with the blends, especially the hydrocarbon blends.
Starting to see a pattern? Everything costs the same no matter what refrigerant you choose to refill with. Add in the better expansion valve (<$30) and a set of charge port adapters (<$15) if you go with R-134a, and you are still way ahead of any of the refrigerant costs of R-12 or the blends. In the end it's a LOT CHEAPER to do the conversion. In my limited experience...
05-07-2008, 07:45 PM
#50
Under the Lift
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I thinl the point that get's lost in all this is that you are adding refrigerant because some or all of your old stuff leaked out. Not many decide to replace or refill their systems "just because". Hard to believe but true! Making an assumption that your system will be leak-free forever is not at all reasonable, so the hydrocarbon and even the other refrigerant blends will cause problems somewhere sometime. Where and when is the remaining question.
Meanwhile, in S4 and later cars with working cooling fans, R-134a provides more than satisfactory performance in a system that's in otherwise good condition. Yes, you will need to reseal the hose connections at minimum. Yes, the compressor oil will need to be changed to one compatible with R-134a. Ideally, at least the high-pressure hoses will be changed, and the expansion valve(s) will be changed. Consider that, since the o-rings need to be changed on the compressor and on the expansion valve connections, you will have these parts loose in your hands, so replacing the oil and putting in new expansion valve(s) is no tougher than reinstalling the old pieces. The labor is exactly the same! Once completed, you have the ability to take your car to any regular AC service place to get it worked on if you have a problem while on the road away from home. There's nothing magical or mysterious about 928 AC compared to any other system in other cars. The compressors are used in lots of other cars, the expansion valves are used in many other common Euro cars, etc. Nothing even remotely exotic.
For some reason we persist in thinking that finding a "drop in" R12 replacement is something just south of the Holy Grail. Once you find it, what will you do with it? Add it to your leaky system? (see first paragraph above...) Drain, reseal, recharge with the "drop in" refrigerant? Why would you even consider that, when R-134a is on the shelf at Wal-Mart and every smaller POLAPS and even the mini-marts along the sides of rural roads?
For those who think that the iso-butane and normal pentane blends are not flamable, drop a line to Louis Ott, or ask the opinions of those who were at the OCIC Dyno Day session a few years ago when only the quick action of a few managed to save his car from burning to the ground when an AC hose got loose. Turns out that the blends burn faster than the paper the data sheets are printed on.
So there....
Meanwhile, in S4 and later cars with working cooling fans, R-134a provides more than satisfactory performance in a system that's in otherwise good condition. Yes, you will need to reseal the hose connections at minimum. Yes, the compressor oil will need to be changed to one compatible with R-134a. Ideally, at least the high-pressure hoses will be changed, and the expansion valve(s) will be changed. Consider that, since the o-rings need to be changed on the compressor and on the expansion valve connections, you will have these parts loose in your hands, so replacing the oil and putting in new expansion valve(s) is no tougher than reinstalling the old pieces. The labor is exactly the same! Once completed, you have the ability to take your car to any regular AC service place to get it worked on if you have a problem while on the road away from home. There's nothing magical or mysterious about 928 AC compared to any other system in other cars. The compressors are used in lots of other cars, the expansion valves are used in many other common Euro cars, etc. Nothing even remotely exotic.
For some reason we persist in thinking that finding a "drop in" R12 replacement is something just south of the Holy Grail. Once you find it, what will you do with it? Add it to your leaky system? (see first paragraph above...) Drain, reseal, recharge with the "drop in" refrigerant? Why would you even consider that, when R-134a is on the shelf at Wal-Mart and every smaller POLAPS and even the mini-marts along the sides of rural roads?
For those who think that the iso-butane and normal pentane blends are not flamable, drop a line to Louis Ott, or ask the opinions of those who were at the OCIC Dyno Day session a few years ago when only the quick action of a few managed to save his car from burning to the ground when an AC hose got loose. Turns out that the blends burn faster than the paper the data sheets are printed on.
So there....
05-08-2008, 02:19 PM
#51
Captain Obvious
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Yes propane is flamable, it has to be to make an internal combustion engine work. Yes farmers use it. I grew up in a farm and we used it in forklifts, tractors and even an old Ford flatbed truck with a carbuerator conversion. I wouldn't want it under pressure in my vehicle though...
05-08-2008, 02:31 PM
#52
Drifting
Louis Ott's car had a fire at the OCIC a few years ago when of the R-12 hydrocarbon-based replacements leaked out of a hose. The story even made it into some AC professional trade mags. Fortunately the fire was extinguished quickly.
http://findarticles.com/p/articles/m...0/ai_n18894615
http://findarticles.com/p/articles/m...0/ai_n18894615
Thanks
