R12 replacements - what works in the 928?
03-29-2007, 01:36 PM
#16
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Nicole--
In spite of some of the horror stories about R-134a not cooling adequately, there are several cars running around with it and some happy customers. I think Bill has one of them, and I have one too.
No matter what refrigerant you choose, your primary task is fixing the leaks. With new o-rings and hoses, and a new drier, you take away a lot of the cost arguments for alternatives. You won't be losing the charge every year when the system is tight. So R12 is then a great choice, especially since that's what all the parts on the car were designed to use. But you must fix all the leaks.
I spent the best part of a day re-doing all the connections, and getting the hoses rebuilt with barrier hose. Pass seat and the rear AC console cover have to come out, in addition to all the parts under the hood.
After all that was done, the refrigerant selection problem for me was not a big issue. I have both R12 and R-134a, and chose R-134a for purely environmental reasons. The performance is sufficient to freeze your fingers on the steering wheel and it easily ices the evaporator when the anti-freeze switch isn't working. So it cycles once the temp in the car is pulled down, and that's where the differences between the refrigerants shows up-- R12 will do that initial cool-down a bit faster than R-134a. How much faster? It's harsd to tell, at least for me, since the AC was leaking when I bought the car. That was in the fall of 1997, and the following spring I did the R-134a conversion before the summer heat set in here. So nine years of trouble-free AC operation for a day's work and a few $hundred in parts/pieces/supplies. I noticed while working on the vent doors that there are a lot of bubbles in the sight glass, so I may need to give the system a puff or two of R-134a before the real summer gets here in SoCal in a few weeks.
I wouldn't even go near any of the substitutes, if for no other reason than you won't be able to get anybody to work on the system for you after you change. I know that with R-134a at least, I can drop into any parts store and buy a can of refrigerant and a little charging kit if some leaks out. I can go to any AC shop and ask them to test the system, and their gauges will read the correct temperatures based on pressures. Oh yeah, so will mine. When you use a blended gas, a leak allows the smaller molecules to escape first so your remaining charge is some unknown composition. Makes problem diagnosis a bit of a chore if you do it right.
The flammability issue of the butane blends is real, even though they state that it isn't. A high-pressure high-concentration leak like Louie experienced in Wichita, onto hot engine parts, will cause a fire. No fun! Of course, R12 will kill you if you chronically breathe vapors that have been superheated across an exhaust manifold, so don't inhale mr president... I believe that flame inhalation is instantly fatal, no forgiveness, so I'd choose the R12 danger given the choice.
My too sense!
In spite of some of the horror stories about R-134a not cooling adequately, there are several cars running around with it and some happy customers. I think Bill has one of them, and I have one too.
No matter what refrigerant you choose, your primary task is fixing the leaks. With new o-rings and hoses, and a new drier, you take away a lot of the cost arguments for alternatives. You won't be losing the charge every year when the system is tight. So R12 is then a great choice, especially since that's what all the parts on the car were designed to use. But you must fix all the leaks.
I spent the best part of a day re-doing all the connections, and getting the hoses rebuilt with barrier hose. Pass seat and the rear AC console cover have to come out, in addition to all the parts under the hood.
After all that was done, the refrigerant selection problem for me was not a big issue. I have both R12 and R-134a, and chose R-134a for purely environmental reasons. The performance is sufficient to freeze your fingers on the steering wheel and it easily ices the evaporator when the anti-freeze switch isn't working. So it cycles once the temp in the car is pulled down, and that's where the differences between the refrigerants shows up-- R12 will do that initial cool-down a bit faster than R-134a. How much faster? It's harsd to tell, at least for me, since the AC was leaking when I bought the car. That was in the fall of 1997, and the following spring I did the R-134a conversion before the summer heat set in here. So nine years of trouble-free AC operation for a day's work and a few $hundred in parts/pieces/supplies. I noticed while working on the vent doors that there are a lot of bubbles in the sight glass, so I may need to give the system a puff or two of R-134a before the real summer gets here in SoCal in a few weeks.
I wouldn't even go near any of the substitutes, if for no other reason than you won't be able to get anybody to work on the system for you after you change. I know that with R-134a at least, I can drop into any parts store and buy a can of refrigerant and a little charging kit if some leaks out. I can go to any AC shop and ask them to test the system, and their gauges will read the correct temperatures based on pressures. Oh yeah, so will mine. When you use a blended gas, a leak allows the smaller molecules to escape first so your remaining charge is some unknown composition. Makes problem diagnosis a bit of a chore if you do it right.
The flammability issue of the butane blends is real, even though they state that it isn't. A high-pressure high-concentration leak like Louie experienced in Wichita, onto hot engine parts, will cause a fire. No fun! Of course, R12 will kill you if you chronically breathe vapors that have been superheated across an exhaust manifold, so don't inhale mr president... I believe that flame inhalation is instantly fatal, no forgiveness, so I'd choose the R12 danger given the choice.
My too sense!
03-29-2007, 01:55 PM
#17
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Tony--
You can pretty easily "top off" your system with the can of gas and a set of chargiing hoses/gauges/manifold. Just be very carefull to bleed all the air out of the hoses before you open the system, or you'll push the air into the system in front of the freon when you start charging. No good way to get the air out once it's in there, short of evacuating and starting over.
If you have leaked down to the point where there is no pressure on the low side on a cold day, you'll really want to evacuate the air out of there with a GOOD vacuum pump. Rob borrows a pump from the lab at the hospital, I have a multi-stage pump lab-quality pump I picked up at an auction. There are various pumps advertized for AC use that are marginal or worse. In the end, you ned to get as much air and water out as possible, and the only way to get real performance out of the system is with a pump that pretty much pegs the gauge on the suction side at 29.9xxx inHg (depending on altitude as you know...) Let it pull on the system overnight before charging to boil off any moisture, then add oil and charge by weight. Oh yeah, a refrigerant scale! That's not on Rob's list yet. Don't forget to replace the drier any time the system pressure has dropped low enough to allow air inside.
There are some pretty good car AC books from Chiltons and others, some may be available from your local library. Does anybody remember those? Places where they warehouse and catalog old books, and let you borrow them to read?
You can pretty easily "top off" your system with the can of gas and a set of chargiing hoses/gauges/manifold. Just be very carefull to bleed all the air out of the hoses before you open the system, or you'll push the air into the system in front of the freon when you start charging. No good way to get the air out once it's in there, short of evacuating and starting over.
If you have leaked down to the point where there is no pressure on the low side on a cold day, you'll really want to evacuate the air out of there with a GOOD vacuum pump. Rob borrows a pump from the lab at the hospital, I have a multi-stage pump lab-quality pump I picked up at an auction. There are various pumps advertized for AC use that are marginal or worse. In the end, you ned to get as much air and water out as possible, and the only way to get real performance out of the system is with a pump that pretty much pegs the gauge on the suction side at 29.9xxx inHg (depending on altitude as you know...) Let it pull on the system overnight before charging to boil off any moisture, then add oil and charge by weight. Oh yeah, a refrigerant scale! That's not on Rob's list yet. Don't forget to replace the drier any time the system pressure has dropped low enough to allow air inside.
There are some pretty good car AC books from Chiltons and others, some may be available from your local library. Does anybody remember those? Places where they warehouse and catalog old books, and let you borrow them to read?
03-29-2007, 04:36 PM
#18
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Tony-
Bob (as usual) hit all the highlights. I did forget to mention the scale, so you can know what mass of refrigerant you're adding. Any 30-50lb postal scale that's good to +/- 1 oz should be fine. We happen to have one in lab that I could use..... The 30lb of R12 I bought is factory fresh, still has the plastic shrinkwrap over the valve.
Adding cans of r134a is very easy, you can buy cans of r134a (interdynamic is the brand) at PepBoyz with a can tap, a short (8") hose and low-side valve. Just run the car at idle, connect the can, tap into it, and put it into a pan of warm water to get it to empty. You will introduce a little air, but this whole kit is cheap if all you have is a slow leak. I have a spare setup sitting around if anyone wants to try it.
With regard to the R12 vs r134a question, if you do it RIGHT and properly prep the system (new o-rings, new drier, evacuate to 30" Hg overnight and ensure that the system HOLDS that vacuum, purge hoses, and fill with an appropriate volume of refrigerant), r134a is clearly adequate, as Bob has said. Honestly, I haven't had the time to play with my car's HVAC system at all. I have vacuum issues, since air blows out the center and doors vents regardless of where you position the slider, and I haven't put gauges on the system to know what my refrigerant charge is. I recently came across a closeout on r134a at the local Target- $2.17 per 12 oz can. I bought all they had- think I bought 9. Once I get around to making the system leakproof (already have the complete front and rear o-ring sets and drier), I may convert to r134a and just re-sell the jug o' R12. I've completely rebuilt an r134a system in my BMW, this stuff isn't hard, just tedious.
Bob (as usual) hit all the highlights. I did forget to mention the scale, so you can know what mass of refrigerant you're adding. Any 30-50lb postal scale that's good to +/- 1 oz should be fine. We happen to have one in lab that I could use..... The 30lb of R12 I bought is factory fresh, still has the plastic shrinkwrap over the valve.
Adding cans of r134a is very easy, you can buy cans of r134a (interdynamic is the brand) at PepBoyz with a can tap, a short (8") hose and low-side valve. Just run the car at idle, connect the can, tap into it, and put it into a pan of warm water to get it to empty. You will introduce a little air, but this whole kit is cheap if all you have is a slow leak. I have a spare setup sitting around if anyone wants to try it.
With regard to the R12 vs r134a question, if you do it RIGHT and properly prep the system (new o-rings, new drier, evacuate to 30" Hg overnight and ensure that the system HOLDS that vacuum, purge hoses, and fill with an appropriate volume of refrigerant), r134a is clearly adequate, as Bob has said. Honestly, I haven't had the time to play with my car's HVAC system at all. I have vacuum issues, since air blows out the center and doors vents regardless of where you position the slider, and I haven't put gauges on the system to know what my refrigerant charge is. I recently came across a closeout on r134a at the local Target- $2.17 per 12 oz can. I bought all they had- think I bought 9. Once I get around to making the system leakproof (already have the complete front and rear o-ring sets and drier), I may convert to r134a and just re-sell the jug o' R12. I've completely rebuilt an r134a system in my BMW, this stuff isn't hard, just tedious.
03-29-2007, 04:55 PM
#19
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EPA 609 certification: $20 (http://www.epatest.com/e_609cert.html)
30 lbs of R12 from Ebay: $300
30 lbs of R12 from Ebay: $300
Were did you see a full can 30lb can of R12 for $300????
Always see 12oz cans for $25-$35.
03-29-2007, 05:32 PM
#20
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John-
Actually, you can buy up to a 20lb container with 609 certification (just looked it up in the study manual I used) Of course, I'm still in violation of that rule, having bought a 30lb tank. I got it in August of '06 off of Ebay, the total was $302 with shipping. The seller was in Minnesota, and his username was something like groggydrunk. So it can be had off of Ebay. In fact, there's one for sale right now (auction 150069344452), thought they want a bit more than $300....
Actually, you can buy up to a 20lb container with 609 certification (just looked it up in the study manual I used) Of course, I'm still in violation of that rule, having bought a 30lb tank. I got it in August of '06 off of Ebay, the total was $302 with shipping. The seller was in Minnesota, and his username was something like groggydrunk. So it can be had off of Ebay. In fact, there's one for sale right now (auction 150069344452), thought they want a bit more than $300....
03-29-2007, 07:21 PM
#21
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Originally Posted by Rob Edwards
Tony-
Bob (as usual) hit all the highlights. I did forget to mention the scale, so you can know what mass of refrigerant you're adding. Any 30-50lb postal scale that's good to +/- 1 oz should be fine. We happen to have one in lab that I could use..... The 30lb of R12 I bought is factory fresh, still has the plastic shrinkwrap over the valve.
Adding cans of r134a is very easy, you can buy cans of r134a (interdynamic is the brand) at PepBoyz with a can tap, a short (8") hose and low-side valve. Just run the car at idle, connect the can, tap into it, and put it into a pan of warm water to get it to empty. You will introduce a little air, but this whole kit is cheap if all you have is a slow leak. I have a spare setup sitting around if anyone wants to try it.
With regard to the R12 vs r134a question, if you do it RIGHT and properly prep the system (new o-rings, new drier, evacuate to 30" Hg overnight and ensure that the system HOLDS that vacuum, purge hoses, and fill with an appropriate volume of refrigerant), r134a is clearly adequate, as Bob has said. Honestly, I haven't had the time to play with my car's HVAC system at all. I have vacuum issues, since air blows out the center and doors vents regardless of where you position the slider, and I haven't put gauges on the system to know what my refrigerant charge is. I recently came across a closeout on r134a at the local Target- $2.17 per 12 oz can. I bought all they had- think I bought 9. Once I get around to making the system leakproof (already have the complete front and rear o-ring sets and drier), I may convert to r134a and just re-sell the jug o' R12. I've completely rebuilt an r134a system in my BMW, this stuff isn't hard, just tedious.
Bob (as usual) hit all the highlights. I did forget to mention the scale, so you can know what mass of refrigerant you're adding. Any 30-50lb postal scale that's good to +/- 1 oz should be fine. We happen to have one in lab that I could use..... The 30lb of R12 I bought is factory fresh, still has the plastic shrinkwrap over the valve.
Adding cans of r134a is very easy, you can buy cans of r134a (interdynamic is the brand) at PepBoyz with a can tap, a short (8") hose and low-side valve. Just run the car at idle, connect the can, tap into it, and put it into a pan of warm water to get it to empty. You will introduce a little air, but this whole kit is cheap if all you have is a slow leak. I have a spare setup sitting around if anyone wants to try it.
With regard to the R12 vs r134a question, if you do it RIGHT and properly prep the system (new o-rings, new drier, evacuate to 30" Hg overnight and ensure that the system HOLDS that vacuum, purge hoses, and fill with an appropriate volume of refrigerant), r134a is clearly adequate, as Bob has said. Honestly, I haven't had the time to play with my car's HVAC system at all. I have vacuum issues, since air blows out the center and doors vents regardless of where you position the slider, and I haven't put gauges on the system to know what my refrigerant charge is. I recently came across a closeout on r134a at the local Target- $2.17 per 12 oz can. I bought all they had- think I bought 9. Once I get around to making the system leakproof (already have the complete front and rear o-ring sets and drier), I may convert to r134a and just re-sell the jug o' R12. I've completely rebuilt an r134a system in my BMW, this stuff isn't hard, just tedious.
03-29-2007, 08:50 PM
#23
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I have plenty of R12 in 12oz or 14oz cans for sale.
Special Spring sale $20 a can.
Special Spring sale $20 a can.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
03-29-2007, 09:39 PM
#24
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Tony:
Yes, the high-side port is near the drier in front of the radiator. The low-side port was strategically located behind tha radiator under all the coolant hoses so you can't get to it without burning the skin off your arm.
Unless you do a lot of systems, it's impractical to buy all the equipment you would need to do this right. A decent vacuum pump is at least $200. You might find one used for far less on eBay, but most of them are not powerful enough. Rob did not mention a halogen sniffer leak detector. Not bad at $25-35 used on eBay. I bought a used R-12 recycler on eBay. These devices are a bit arcane and the instruction manuals don't cover all the fine points of their use. I found a 55 lb scale accurate to 0.1 oz pretty cheaply, again on eBay, for use with my 30 lb cannister.
Nicole:
All of these 400 series replacements are butane, propane or isobutane mixtures. The manufacturers' claims of low flammability appear to be based on ignition point in a closed system. With a leak, like Louie had, these things burn much better than Freon.
Yes, the high-side port is near the drier in front of the radiator. The low-side port was strategically located behind tha radiator under all the coolant hoses so you can't get to it without burning the skin off your arm.
Unless you do a lot of systems, it's impractical to buy all the equipment you would need to do this right. A decent vacuum pump is at least $200. You might find one used for far less on eBay, but most of them are not powerful enough. Rob did not mention a halogen sniffer leak detector. Not bad at $25-35 used on eBay. I bought a used R-12 recycler on eBay. These devices are a bit arcane and the instruction manuals don't cover all the fine points of their use. I found a 55 lb scale accurate to 0.1 oz pretty cheaply, again on eBay, for use with my 30 lb cannister.
Nicole:
All of these 400 series replacements are butane, propane or isobutane mixtures. The manufacturers' claims of low flammability appear to be based on ignition point in a closed system. With a leak, like Louie had, these things burn much better than Freon.
03-29-2007, 09:46 PM
#25
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Where's Nicole?
Anyway, when you get here, look at my link below. These people have a lot of experience, and I'm sure they mean well...but they aren't as good as the folks at Griffiths!
http://www.griffiths.com/achelp/achelp3.html
N!
Anyway, when you get here, look at my link below. These people have a lot of experience, and I'm sure they mean well...but they aren't as good as the folks at Griffiths!
http://www.griffiths.com/achelp/achelp3.html
N!
Isceon49
03-29-2007, 11:07 PM
#28
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Normy,
Please don't take this the wrong way but why are you so condescending of the membership?
I do not know you from Adam but that is twice you have been rude to me and the membership.
Why are you so special?
Roger
Please don't take this the wrong way but why are you so condescending of the membership?
I do not know you from Adam but that is twice you have been rude to me and the membership.
Why are you so special?
Roger
03-29-2007, 11:11 PM
#29
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Originally Posted by Normy
Where's Nicole?
Anyway, when you get here, look at my link below. These people have a lot of experience, and I'm sure they mean well...but they aren't as good as the folks at Griffiths!
http://www.griffiths.com/achelp/achelp3.html
N!
Anyway, when you get here, look at my link below. These people have a lot of experience, and I'm sure they mean well...but they aren't as good as the folks at Griffiths!
http://www.griffiths.com/achelp/achelp3.html
N!
03-29-2007, 11:23 PM
#30
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OK, OK, let me explain why I asked this question... R12 is banned in many parts of the world. No more. So people find alternatives that are friendlier to the environment.
I personally believe that I should conduct my activities with no more negative impact on the environment than absolutely necessary. Which is why I recycle when I can, have fully functioning emissions controls including cats in my cars, and asked about an alternative to R12.
The German 928 owners have switched to R413 - for them it has become a pretty "normal" thing to use. Yet, I have never heard about it here; don't even know, if it's available.
If R413 or a similar susbtitute WAS available and would not pose any significant risk to the health of myself and my car, I would certainly be interested in switching to it when the system needs to be evacuated and recharged next time - regardless of whether R12 is still available for cheap or not (I'd expect the substitutes to be equal or less in price).
Call me a tree hugger, if you feel like; I don't see myself as extreme in any way. For me it's just a reasonable thing to consider and contribute my part to reducing FCKWs in the atmosphere.
So, I really wasn't looking for info on how cheap R12 is - I was hoping that someone out there has tried a good substitute (not what Louie used) and had anything to say about it.
Thanks, joejoe and UKKid35 for sharing your experiences!
I personally believe that I should conduct my activities with no more negative impact on the environment than absolutely necessary. Which is why I recycle when I can, have fully functioning emissions controls including cats in my cars, and asked about an alternative to R12.
The German 928 owners have switched to R413 - for them it has become a pretty "normal" thing to use. Yet, I have never heard about it here; don't even know, if it's available.
If R413 or a similar susbtitute WAS available and would not pose any significant risk to the health of myself and my car, I would certainly be interested in switching to it when the system needs to be evacuated and recharged next time - regardless of whether R12 is still available for cheap or not (I'd expect the substitutes to be equal or less in price).
Call me a tree hugger, if you feel like; I don't see myself as extreme in any way. For me it's just a reasonable thing to consider and contribute my part to reducing FCKWs in the atmosphere.
So, I really wasn't looking for info on how cheap R12 is - I was hoping that someone out there has tried a good substitute (not what Louie used) and had anything to say about it.
Thanks, joejoe and UKKid35 for sharing your experiences!
Last edited by Nicole; 03-30-2007 at 01:45 AM.