Long story, A/C advice needed
07-09-2008, 11:08 AM
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Long story, A/C advice needed
Hey Guys, I am needing some more of your expert advice for my 92 100cs Q.
About three years ago i had the A/C charged with R12 and it worked fine but over time it just kinda gave up so a couple of months ago i took it into a shop to have them recharge the system, They charged it with R134a but i don't think they evacuated the system. It worked great for about 24 hours then gave up completely. I then took it to a shop that just works on Audi's and they told me that the compressor was bad because the system was only charged with 134 and not properly converted. They said that Now i needed to change the compressor, the dryer and and have the system gone through for about $1200.
Anyway i brought the car home and started to swap out the compressor for a good compressor from a 94 and found that the fittings for the high and low lines were different so i couldn't put the new compressor in. Also when i took off the old compressor their was quite a bit of pressure in both lines. Are the check valves to keep the pressure difference in the compressor or somewhere else? Also could i simply take the backs off of both compressors and swap them so i get the right connections? also can you really mess up the system by just charging with r134 and not r12. the shop said that the 134 molecules are smaller and leak out and cause things to go bad, i thought that people convert the systems all the time.
Since there was so much pressure in both lines it leeds me to think that there are some check valves that aren't working quite right, or that they just over charged the system to the point where there is not enough pressure difference from high to low.
I really haven't done much at all with AC so don't know much about it but would like to get it working for a reasonable price. if not i'll just run it without the ac i guess.
Cheers
Devon
About three years ago i had the A/C charged with R12 and it worked fine but over time it just kinda gave up so a couple of months ago i took it into a shop to have them recharge the system, They charged it with R134a but i don't think they evacuated the system. It worked great for about 24 hours then gave up completely. I then took it to a shop that just works on Audi's and they told me that the compressor was bad because the system was only charged with 134 and not properly converted. They said that Now i needed to change the compressor, the dryer and and have the system gone through for about $1200.
Anyway i brought the car home and started to swap out the compressor for a good compressor from a 94 and found that the fittings for the high and low lines were different so i couldn't put the new compressor in. Also when i took off the old compressor their was quite a bit of pressure in both lines. Are the check valves to keep the pressure difference in the compressor or somewhere else? Also could i simply take the backs off of both compressors and swap them so i get the right connections? also can you really mess up the system by just charging with r134 and not r12. the shop said that the 134 molecules are smaller and leak out and cause things to go bad, i thought that people convert the systems all the time.
Since there was so much pressure in both lines it leeds me to think that there are some check valves that aren't working quite right, or that they just over charged the system to the point where there is not enough pressure difference from high to low.
I really haven't done much at all with AC so don't know much about it but would like to get it working for a reasonable price. if not i'll just run it without the ac i guess.
Cheers
Devon
07-09-2008, 12:59 PM
#2
Mmm......
No, there are not check valves. You had a system that was still partially charged when you opened it up.
Can you switch the backs of the compressor? Not likely, but maybe. You'll probably end up with a compressor that leaks from that seam....it the internals are the same and you can even swap.
What I would do:
I'd put the system back together with the old compressor.
I'd buy one of the air compressor driven vacuum pumps that harbor freight sells for $10, and a set of a/c gauges. I'd suck the system down for an hour to boil out all the air and moisture, close off the a/c gauge valves, and sit and watch if the vacuum leaks off to zero, over a 24hr period.
When the system was apart, I'd replace as many o-rings as I could get to with the green viton ones.
If the system holds a vacuum, I'd add a few ounces of Ester 100 Synthetic oil (a/c oil from your local auto parts store) and then run in 3 cans of 134a and see what it does. You can buy the conversion kits from Walmart, NAPA, or any other auto parts store and that'll get you 3 cans of refrigerant and a can of refrigerant with oil and dye in it.
Can you switch the backs of the compressor? Not likely, but maybe. You'll probably end up with a compressor that leaks from that seam....it the internals are the same and you can even swap.
What I would do:
I'd put the system back together with the old compressor.
I'd buy one of the air compressor driven vacuum pumps that harbor freight sells for $10, and a set of a/c gauges. I'd suck the system down for an hour to boil out all the air and moisture, close off the a/c gauge valves, and sit and watch if the vacuum leaks off to zero, over a 24hr period.
When the system was apart, I'd replace as many o-rings as I could get to with the green viton ones.
If the system holds a vacuum, I'd add a few ounces of Ester 100 Synthetic oil (a/c oil from your local auto parts store) and then run in 3 cans of 134a and see what it does. You can buy the conversion kits from Walmart, NAPA, or any other auto parts store and that'll get you 3 cans of refrigerant and a can of refrigerant with oil and dye in it.
07-09-2008, 02:19 PM
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Thanks Todd, I'll try that and see what happens
One shop i talked to said that the compressors are pretty solid units and that they don't need replacing that often. so that would be great. I don't really want to break open the compressor if i don't have to, since i was afraid that it would leak around that seal like you said.
Cheers
Devon
Cheers
Devon
07-10-2008, 04:37 AM
#4
Agreed. I'll add:
The original problem was probably a bad condenser unit or evaporatorand still has not been addressed. In addition to your compressor issues, you need to find the leak.
The two compressors are different because the 94 compressor is a 134a unit. The internals may or may not be the same as the old r-12 unit.
Good luck with this. You have a long road ahead. The guy that dumped the 134 into the system really did you no favors. I am 100% against converting R-12 to 134a.
The two compressors are different because the 94 compressor is a 134a unit. The internals may or may not be the same as the old r-12 unit.
Good luck with this. You have a long road ahead. The guy that dumped the 134 into the system really did you no favors. I am 100% against converting R-12 to 134a.
07-10-2008, 08:58 AM
#7
Exactly. This is what you're looking for when you evacuate the system...
If it won't hold a vacuum, you know you have leaks. The only way to find them is to put in some fluorescing dye (you can buy a dye installer with dye cans) and then charge the system, sniff it with a freon sniffer, and fix what you find with that........evac and recharge the system, sniff again, and then check for leaks with a black light after driving it a few weeks.
You can buy the freon sniffers on ebay for cheap.
You can buy the freon sniffers on ebay for cheap.
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