Well I've done it now. After restoring all of the front suspension components, and all of the power steering(control valve leaks out of adjustment port, will have to investigate); I started to replace the rad. hoses and looked in the radiator....horrors! After finding out you have remove the hood and unbolt the support bracket, I removed the rad. to be redone? Now my problem is the car is on jackstands, with no radiator; and this seems like a perfect time to "fix" the AC(it has no pressure). I can't pump it down without a vacuum pump, and can't move the thing. R12 is expensive to use for leak testing, not to mention the epa, ozone, and the Dupont R12 patent running out. So I'll clean out the system and recharge with new oil and R134A(i have no access to Forane). If I need to go back to R12 because of the hoses(no liner) or inadequate cooling; is R12 compatible with the oil used for R134? I know that R134 is not compatible with R12 oil. TIA Jim
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Re: troubleshooting R12 AC on a 75
No, the 2 oils are not compatible. That said, most mechanics I know are not real fussy about getting the old oil out when changing from R-12 to R-134. They just disconnect a hose and let the old oil drain. Then they put in the new oil. I would think that if you changed the dryer/reservoir/accumulator and blew out various sections of the system while it was open, that you would have gotten enough of the old oil out so that you could change over. Most of the oil would be in the dryer and the compressor. If you take the hoses off the compressor and spin it, most of the old oil will come out. There is a flushing fluid which is made for this purpose. -
Re: troubleshooting R12 AC on a 75
No, the 2 oils are not compatible. That said, most mechanics I know are not real fussy about getting the old oil out when changing from R-12 to R-134. They just disconnect a hose and let the old oil drain. Then they put in the new oil. I would think that if you changed the dryer/reservoir/accumulator and blew out various sections of the system while it was open, that you would have gotten enough of the old oil out so that you could change over. Most of the oil would be in the dryer and the compressor. If you take the hoses off the compressor and spin it, most of the old oil will come out. There is a flushing fluid which is made for this purpose.Comment
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Re: troubleshooting R12 AC on a 75
I'm replacing all of the o-rings and schrader valves. I know enough about AC to be dangerous, and have done numerous fixes in the past. I have read that R134 is not compatible with the oil that was used with R12. I wondered if R12 was compatible with PAG oil used with R134 systems, or if it was compatible with R12 itself. There are a lot of older systems that have R134 in them but have the older fittings, and unless you find that label; you could accidently put R12 into an R134 system very easily. I guess I'll just bite the bullet and have new hoses crimped on the old fittings(still in great shape) where it would be painful to get at if I didn't have the hood and radiator off. The core on my rad. turned out to be shot, so I told the guy to replace the core and preserve all of the tags, etc. when he puts the new core in. Of course since I have gone this far.....might as well replace all the seals, replace that leaking front crankshaft seal,....does it ever end? I WANT TO DRIVE THE CAR!Comment
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Re: troubleshooting R12 AC on a 75
I'm replacing all of the o-rings and schrader valves. I know enough about AC to be dangerous, and have done numerous fixes in the past. I have read that R134 is not compatible with the oil that was used with R12. I wondered if R12 was compatible with PAG oil used with R134 systems, or if it was compatible with R12 itself. There are a lot of older systems that have R134 in them but have the older fittings, and unless you find that label; you could accidently put R12 into an R134 system very easily. I guess I'll just bite the bullet and have new hoses crimped on the old fittings(still in great shape) where it would be painful to get at if I didn't have the hood and radiator off. The core on my rad. turned out to be shot, so I told the guy to replace the core and preserve all of the tags, etc. when he puts the new core in. Of course since I have gone this far.....might as well replace all the seals, replace that leaking front crankshaft seal,....does it ever end? I WANT TO DRIVE THE CAR!Comment
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Re: troubleshooting R12 AC on a 75
Just a side note here. I am having my 77 Buick converted to use the new 134 freon. The AC shop will clean and purge the old compressor to remove the old oil and then refill with the new oil and freon. He has also converted my neighbor's 73 Corvette coupe with the same type of kit.Comment
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Re: troubleshooting R12 AC on a 75
Just a side note here. I am having my 77 Buick converted to use the new 134 freon. The AC shop will clean and purge the old compressor to remove the old oil and then refill with the new oil and freon. He has also converted my neighbor's 73 Corvette coupe with the same type of kit.Comment
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Re: troubleshooting R12 AC on a 75
The PAG oil IS NOT compatible with the R12 or the R12 oil. When converting to 134 you should remove as much of the R12 oil as "reasonably" possible, and replace it with ESTER refrigerant oil. This oil is available at most any auto parts store. ESTER oil is formulated to work with both R12 and R134 components. Make sure you use a R134 compatible reciever drier, and you only need to charge your system with 85-90% of R134 freon as compared to R12. The reason behind using 10-15% less freon is that R134 has a greater expansion rate than R12. This is also a good time to examine your shroud and fan clutch. in order to achieve R12 AC performance from R134 you need to make sure you have excellent flow through your ac condenser.
DennisComment
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Re: troubleshooting R12 AC on a 75
The PAG oil IS NOT compatible with the R12 or the R12 oil. When converting to 134 you should remove as much of the R12 oil as "reasonably" possible, and replace it with ESTER refrigerant oil. This oil is available at most any auto parts store. ESTER oil is formulated to work with both R12 and R134 components. Make sure you use a R134 compatible reciever drier, and you only need to charge your system with 85-90% of R134 freon as compared to R12. The reason behind using 10-15% less freon is that R134 has a greater expansion rate than R12. This is also a good time to examine your shroud and fan clutch. in order to achieve R12 AC performance from R134 you need to make sure you have excellent flow through your ac condenser.
DennisComment
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Re: troubleshooting R12 AC on a 75
Sorry i said pag oil; it had been a long day. Thanks for the answer; which is that r12, and 134 are compatible with ester based oil. This would seem to imply an easier path if one had to go back to R12.
Is there a description somewhere of the accumulator gizmo; and is the VIR valve in it or still in the bowels of the evaporator on the firewall? I had quite a bit of brown dust inside along with oil, which leads me to the conclusion that the compressor has bought it. I really do not want to remove the housing on the firewall unless absolutely necessary. However if an expansion valve is in there, i probably can't just flush it out with some ac cleaner.Comment
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Re: troubleshooting R12 AC on a 75
Sorry i said pag oil; it had been a long day. Thanks for the answer; which is that r12, and 134 are compatible with ester based oil. This would seem to imply an easier path if one had to go back to R12.
Is there a description somewhere of the accumulator gizmo; and is the VIR valve in it or still in the bowels of the evaporator on the firewall? I had quite a bit of brown dust inside along with oil, which leads me to the conclusion that the compressor has bought it. I really do not want to remove the housing on the firewall unless absolutely necessary. However if an expansion valve is in there, i probably can't just flush it out with some ac cleaner.Comment
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