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A/C question on SC
I was in the process of going thru A/C system on my 82,change drier put sys on vacuum pump, leak check and give her a fresh charge of 134. Ran it to a snag, I have not looked real hard can someone tell me where is the drier located??
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front left wheel well.
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Pete 79 911SC RoW "Tornadoes come out of frikkin nowhere. One minute everything is all sunshine and puppies the next thing you know you've got flying cows".- Stomachmonkey |
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did you convert to 134?
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Thanks Pete, No I didnot do the conversion to 134A however not really that hard to do. It was kinda a racket thing buy the auto industry 134 operates close to R12 pressures. If you want to convert they make the compressors and you will need to replace , expansion valve in comportment in trunk will need to be replaced. You should replace drier. Recommend hooking system to a vacuum pump and pulling sys down to 500 microns or about 25 inchs of vacuum for a couple of hours. Then you will need to charge system with hood down in engine compartment. You will need to have evaporator pressures between 25 to 35 lbs. Make sure to keep Head Pressures below 200lbs in will very as the ambient temp outside will affect pressures. Charge system only on low side suction
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40 to 50 microns for three hours is required to get the non-condensible gasses down and the water out of a 911 system; 25 inches of vacuum being adequate is a function of altitude. Not enough at sea level and impossible at my altitude. Failure to change out (flush at least the condensers) the mineral oil with an R-134a compatible oil is the origin of compressor failure and lousy heat transfer. The desiccant in an old R-12 R/D is likely not compatible with R-134a.
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I didnot do the conversion to 134A however not really that hard to do.
![]() ![]() ![]() ![]() ![]() Last edited by ueritaGro; 05-15-2012 at 07:02 PM.. |
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Harder than you might think on an SC.. To do it correctly anyway.
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2021 Model Y 2005 Cayenne Turbo 2012 Panamera 4S 1980 911 SC 1999 996 Cab |
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^^^^+!.. It's not a 'racket'.. I would recommend using Freeze 12, if you don't want to do a proper conversion..
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All refrigerant is a racket and about money and lobbist. Dupont is making a fortune on the green planet. For those who do not want to do the conversion ,MP39 is the drop for R12, as far as the oil you just need to add a little POE oil the reason is not heat transfer that is done with the superheat adjustment of the expansion valve. POE allows for oil return to compressor due to the glide change of 134 a
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A/C hoses..........
The original hoses should also be changed out to a barrier type hose. Otherwise, the smaller R134 molecules will find their way out thru the more porus hose material. When I did the changeover on my SC, I pulled the hoses, cut the crimps and reused the threaded ends by crimping them into new barrier hose. My local NAPA store had the hoses in the correct size and let me use their hydralic hose crimping machine to reattach the ends. The suprise was the one hose that runs from the engine compartment to the front condenser! Turned out to be about 16 feet long!
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I wouldn't switch from R12 without adding condensers
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