A/C Compressor Seal? R134 R12? Huh?
06-06-2002, 09:33 AM
#31
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I finished installing my new Compressor, hoses, and Dryer last night.
Just need to get to the Rear A/C TXV and replace it as well then I can hook up the Vacuum Pump. Already replaced the front TXV - one made for R134. Looks like when they (who ever 'they' are) did the conversion, some of the orings were not replaced (and most likely the TXV's weren't either).
Hopefully I'll have positive results to post come next week.
Just need to get to the Rear A/C TXV and replace it as well then I can hook up the Vacuum Pump. Already replaced the front TXV - one made for R134. Looks like when they (who ever 'they' are) did the conversion, some of the orings were not replaced (and most likely the TXV's weren't either).
Hopefully I'll have positive results to post come next week.
06-06-2002, 06:14 PM
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It's not to hard with cars, superheat and subcooling. Superheat is what makes the TXV determine the size of the orfice. Yes you can charge the system by superheat. Not hard to figure the superheat standing still, Your not charging the system with the car going down the raod. (PS, the only systems I am aware of that you can not charge by super heat are the Absorbers, Centrifugals, Recip's, and Screws. There may be more, But the brain is shutting down. I am running on 18 hour workd days for days on end.)
I didn't say I charged all these ways on the Sharks.
Secondly playing with weight is good way too.
Other cars YMM may vary, but you CAN charge the system by amp draw.
John D.
'85 928 Auto
One must remember how the system actually works. With a txv (a txv determines the system capacity) The txv relies on the superheat of the system to determine what capacity to run at.
I didn't say I charged all these ways on the Sharks.
Secondly playing with weight is good way too.
Other cars YMM may vary, but you CAN charge the system by amp draw.
John D.
'85 928 Auto
One must remember how the system actually works. With a txv (a txv determines the system capacity) The txv relies on the superheat of the system to determine what capacity to run at.
06-06-2002, 06:42 PM
#33
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J.D. wrote:
[quote] Other cars YMM may vary, but you CAN charge the system by amp draw.
<hr></blockquote>
John, you've got me stumped on this one. The only current draw that's related to the 928 compressor is the clutch coil. The current through that is pretty darn constant regardless of AC load or charge level. While there is a definite inductive/reactive component to the electrical impedance of the coil, none of that really changes based on refrigerant charge levels.
Am I missing some critical function here?
<img src="confused.gif" border="0">
[quote] Other cars YMM may vary, but you CAN charge the system by amp draw.
<hr></blockquote>
John, you've got me stumped on this one. The only current draw that's related to the 928 compressor is the clutch coil. The current through that is pretty darn constant regardless of AC load or charge level. While there is a definite inductive/reactive component to the electrical impedance of the coil, none of that really changes based on refrigerant charge levels.
Am I missing some critical function here?
<img src="confused.gif" border="0">
06-06-2002, 07:16 PM
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Michael from Denmark asks about alternatives to R-134a in conversions.
For owners in the U.S., the biggest issue is availability of service on a system after the conversion is done. The places that service auto AC systems are equipped to handle R-12 and R-134a only. Anything else in the system makes it contaminated, and they aren't allowed to work on it legally until the contaminated charge is removed.
So, how about some thougts for US car owners contemplating alternatives. Besides the issue stated above...
Yo are working on the system and contemplating a conversion because there are leaks that caused you to lose your R-12. Folks suggest that replacing the o-rings and hoses for the R-134a conversion is too much aggravation. My question-- How do you plan to cure the leaks at the connections without o-ring replacement? You definitely want to fix those leaks, right?
While stuff is disconnected for the new o-rings, have the hoses rebuilt so that they don't leak. While that same stuff is disconnected, drain all the old oil out, and plan on replacing it with new fresh stuff when you recharge. Hmmm, polyolester or mineral oil? Toughest choice...
My speculation is that, if R-409 or 412 was suitable for use as an R-12 replacement, car manufacturers and the aftermarket would jump on them and develop kist to support the conversions. So far, the efforts at finding 'other' replacements have focused on blends of materials like iso-butane and pentane. The different molecules seem to find different size holes to leak through at different rates, upsetting the blend and therefore the performance.
I do want to mention that, were it not for the giant mobile BIC lighter effect, isobutane would probably be the binary fluid of choice for cooling the car. Most sources of isobutane have already been contaminated with propane, which diminishes the efficiency of the process because of the differences in condensing and boilng tems vs pure isobutane. The effect is similar to the effect of having air in your freon system, perhaps two degrees of evaporator temp penalty for each inch partial pressure of the contaminant gas.
Anybody still reading....?
For owners in the U.S., the biggest issue is availability of service on a system after the conversion is done. The places that service auto AC systems are equipped to handle R-12 and R-134a only. Anything else in the system makes it contaminated, and they aren't allowed to work on it legally until the contaminated charge is removed.
So, how about some thougts for US car owners contemplating alternatives. Besides the issue stated above...
Yo are working on the system and contemplating a conversion because there are leaks that caused you to lose your R-12. Folks suggest that replacing the o-rings and hoses for the R-134a conversion is too much aggravation. My question-- How do you plan to cure the leaks at the connections without o-ring replacement? You definitely want to fix those leaks, right?
While stuff is disconnected for the new o-rings, have the hoses rebuilt so that they don't leak. While that same stuff is disconnected, drain all the old oil out, and plan on replacing it with new fresh stuff when you recharge. Hmmm, polyolester or mineral oil? Toughest choice...
My speculation is that, if R-409 or 412 was suitable for use as an R-12 replacement, car manufacturers and the aftermarket would jump on them and develop kist to support the conversions. So far, the efforts at finding 'other' replacements have focused on blends of materials like iso-butane and pentane. The different molecules seem to find different size holes to leak through at different rates, upsetting the blend and therefore the performance.
I do want to mention that, were it not for the giant mobile BIC lighter effect, isobutane would probably be the binary fluid of choice for cooling the car. Most sources of isobutane have already been contaminated with propane, which diminishes the efficiency of the process because of the differences in condensing and boilng tems vs pure isobutane. The effect is similar to the effect of having air in your freon system, perhaps two degrees of evaporator temp penalty for each inch partial pressure of the contaminant gas.
Anybody still reading....?
06-06-2002, 11:02 PM
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No, your not missing something. Maybe I was not concise with my words. I have charged a few other makes of vehicles by amp draw at the motor. I have not attempted to charge my shark a/c this way. Due to the ease of charging the system by weight with a few ounces more for what I feel is adequate air.
Keep in mind I still need to replace my motor mounts, and a few other things that are causing me some added interior heat. But, these problems will be a winter project when the engine gets pulled for 'SOME' work.
John D.
'85 928 Auto, Black
Keep in mind I still need to replace my motor mounts, and a few other things that are causing me some added interior heat. But, these problems will be a winter project when the engine gets pulled for 'SOME' work.
John D.
'85 928 Auto, Black
06-07-2002, 01:43 AM
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hey doz, please keep us posted on this winter project. namely the prep work up to engine pull and beyond. i'm looking at similar work a summer or two from now.
06-07-2002, 04:17 AM
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DR Bob
Aren't flammable gasses illegal to use for refrigeration in cars (in america). I read up on this a while back, and I think I remember something like that.
FWIW you too can buy r12 legally in the states by taking a test at <a href="http://www.epatest.com" target="_blank">www.epatest.com</a> or the like. =) Still have to buy the charging equipment though.
Jim Wilson
'79 Euro 5
Aren't flammable gasses illegal to use for refrigeration in cars (in america). I read up on this a while back, and I think I remember something like that.
FWIW you too can buy r12 legally in the states by taking a test at <a href="http://www.epatest.com" target="_blank">www.epatest.com</a> or the like. =) Still have to buy the charging equipment though.
Jim Wilson
'79 Euro 5
06-07-2002, 03:31 PM
#39
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On buying R-12 after passing the test--
My earlier point was that the reason you are even reading the discussion is because you have a leak someplace that's causing you to look at charging the system again. So do you find and fix just that one leak, or do you bite the bullet and replace all the seals and the hoses at one tims? R-12 systems always leak, and maintenance has been a requirement since day one. Now that R-12 is on the green **** list, that maintenance has become impractical for most folks. Yes I can take the test, and then I can buy R-12 for inflated prices and an escalating tax penalty. To comply with the law, I need to have certified recovery equipment, etc, that's out of reach of the weekend AC guy.
I did take the online test a while ago, passed and have the certification, but have never used it to buy R-12. Once I decided to fix all the leaks and replace the hoses, R-134a was the weapon of choice based on gas purchase cost alone. The (supposed) environmental factors are a fringe benefit.
We have an aquaintance who has been studying sun-spot activity and the relationship to atmospheric conditions and "global warming" from ozone depletion and greenhouse gasses. Her research suggests that the theories of effects of flourocarbons on the ozone and greenhouse gasses on inversion stuff are, well, junk. Pretty interesting stuff, looking at sunspot trends related to climate changes over the last several hundred years. But, it would put whole scientific groups and government agencies out of business, so it can't be true.
Stay Cool!
dr bob
My earlier point was that the reason you are even reading the discussion is because you have a leak someplace that's causing you to look at charging the system again. So do you find and fix just that one leak, or do you bite the bullet and replace all the seals and the hoses at one tims? R-12 systems always leak, and maintenance has been a requirement since day one. Now that R-12 is on the green **** list, that maintenance has become impractical for most folks. Yes I can take the test, and then I can buy R-12 for inflated prices and an escalating tax penalty. To comply with the law, I need to have certified recovery equipment, etc, that's out of reach of the weekend AC guy.
I did take the online test a while ago, passed and have the certification, but have never used it to buy R-12. Once I decided to fix all the leaks and replace the hoses, R-134a was the weapon of choice based on gas purchase cost alone. The (supposed) environmental factors are a fringe benefit.
We have an aquaintance who has been studying sun-spot activity and the relationship to atmospheric conditions and "global warming" from ozone depletion and greenhouse gasses. Her research suggests that the theories of effects of flourocarbons on the ozone and greenhouse gasses on inversion stuff are, well, junk. Pretty interesting stuff, looking at sunspot trends related to climate changes over the last several hundred years. But, it would put whole scientific groups and government agencies out of business, so it can't be true.
Stay Cool!
dr bob
06-07-2002, 04:38 PM
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I don't want to turn this into an environmental thread, but there was a brief mention in the news not too long ago that the CO ice caps on Mars were melting at an increasing rate. I kind of wonder how the environmentalists are going to try and blame that on something we did too.
06-07-2002, 05:45 PM
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DR BOB, Spot on. The theories and fact finding studies benefit the 'BIG' corporations, and the tax man. When the fact finding mission is clouded by the funding it receives, you know what the outcome will be before it's found.
John D.
'85 928 Auto, Black
John D.
'85 928 Auto, Black
06-08-2002, 01:00 PM
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MIke wrote:
[quote] I don't want to turn this into an environmental thread, but there was a brief mention in the news not too long ago that the CO ice caps on Mars were melting at an increasing rate. I kind of wonder how the environmentalists are going to try and blame that on something we did too.<hr></blockquote>
See this is the kind of stuff that scientific legends are made of.
It goes like this-- As the CO2 caps start to melt, the (greenhouse...) gases migrate to the upper atmospheres of the planet, causing additional warming, which in turn melts more ice to make more gas. Won't be long berore we have a total thermal runaway, and the red glow of Mars is more than the reflection from the ferrous compounds near the planets soon-to-be-less-than-solid surface.
It will all come true in the next 4 billion years, mind you. Remember, you heard it here first!
Cheers!
[quote] I don't want to turn this into an environmental thread, but there was a brief mention in the news not too long ago that the CO ice caps on Mars were melting at an increasing rate. I kind of wonder how the environmentalists are going to try and blame that on something we did too.<hr></blockquote>
See this is the kind of stuff that scientific legends are made of.
It goes like this-- As the CO2 caps start to melt, the (greenhouse...) gases migrate to the upper atmospheres of the planet, causing additional warming, which in turn melts more ice to make more gas. Won't be long berore we have a total thermal runaway, and the red glow of Mars is more than the reflection from the ferrous compounds near the planets soon-to-be-less-than-solid surface.
It will all come true in the next 4 billion years, mind you. Remember, you heard it here first!
Cheers!
