M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => General Topics => Topic started by: nomad on July 02, 2007, 07:17:33 PM
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So what have folks paid for both a shop to do it or to buy the parts yourself and redo it?
It's 105 here today and i just don;t think I'll make it through the summer with vinyl seats...
A/C doesn't work at all and I'm sure it's still R12.
I want longevity so from what i read I could buy a compressor for $300? Get an o-ring kit for $40? and then a dryer for $50? Mess with it myself and try to get it to work, then get it filled with R134
Or I could take it to a local mech and tell them to "make it work".
I also heard from some folks that the M42 compressor is R134 compatible if you just do a $40 o-ring kit and dryer? The only thing I'd worry about would be the expansion valves and the hoses leaking.
What's the concensus?
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OK, so I read as many old posts as I could find and decided I'd go to wal mart tonight and get the kit. I got an a/c retrofit kit for conversion from R-12 to R-134a. It's the kit in a box that has three cans of R134a, 10oz each I think, plus the two fittings for the high and low side along with the nice tester/guage/applicator nozzle and an instruction CD. All that for $34.
I've used the other cheaper ones before but this nozzle is nicer in that it has a trigger and it large and screws onto the top of the cans.
The low side fitting fit right on the schrader valve. The high side will not fit though, it is too small.
The charge didn't even register on the guage when I started the car. I emptied one can into the car and the pressure went up to 45psi. So that is what it calls full charge.
The air definitely blows cooler than before (previously it felt hotter than ambient) but not icey or anything. I'll drive it around tomorrow in 104 degree temps and see how it feels before I go dropping it off at a shop.
I'll report back. I don't know if I should have them vacuum the system or something to make it work better. I really don't know if anything was in there before. I also don't know if I have a leak and may lose whatever i put in.
I'll report back what I find.
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I'm not sure if all E30 M42 came with R134 compatible compressors or not but you can check for the label on the compressor. I also bought a $32 conversion kit from Autozone but this particular one had a special conversion oil that is suppose to mix with the old R12 oil so the seals don't deteriorate and leak from the new oil. I figured it would be a safety thing if anything. I believe our systems take around 29 oz of refrigerant so I just put in 2 12oz and called it a day. So far so good...
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So do you think the pressure reading on the guage in the kit should be followed? It is now right at 45psi and after that is supposedly the "be careful" zone.
I think I'll monitor it for now.
How do you know if the system is filled correctly? I always think of whatever was in there before - R-12 or just stale air - is taking up space and when I'm adding I should also be taking out the old fluid or air. Is this accurate?
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I was thinking of getting the retrofit kit listed below (scroll to the bottom)
http://www.koalamotorsport.com/article-airconditioning.asp
The kit is $177 and the oil is $63 at pelican parts.
Instructions are here:
http://www.pelicanparts.com/bmw/techarticles/101-Projects-97-AC/101-Projects-97-AC.htm
To summarize:
1. Recycle r12 (have shop do it)
2. Swap out compressor if not compatible (if it's a 1991 318is then it's compatible, but check the table just in case)
3. Swap out the o-rings and install new parts from the retro-fit kit
4. Have shop vacuum out system for 40 mins
5. Recharge with r134
6. Change out compress oil.
7. Test the sysem
Looks doable. Step 6 seems like an after thought, can a weekend warrior recharge the oil in the compressor or will you need specialized tools/machines? My air doesn't blow cold at all, so I am going to skip step 1, I bet there isn't any freon left. What's step 4 for? Is that to dry out the system and check for leaks? The shop I go to wants $70 just to turn a machine on.. I'm sure I'll be a 100-200 poorer afterwards.
Alternatively, talking to several shops, wheather or not you supply the parts, the labor will exceed $500 in the san diego area. So the retrofit kit is looking pretty good at this point.
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Step 4 is removing everything from your ac system, old refrigerent, most of the oil and contaminents. This step here can make your ac work as it should. you should also replace the drier. Think of ther drier as a sort of filter.
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Before you start tearing into your AC you should do some basic diagnostics. Can you turn the AC compressor by hand? Is there pressure in the system? Is the compressor receiving power signal from the computer? If you are just down on pressure, try hot wiring the compressor clutch to see if it will spin. You can top off your AC with any number of HC refrigerants like Duracool or freeze12 without having to convert to R134. Mine was simply down on pressure and the AC relay under the dash wasn't working. I hot wired the AC compressor to run off the low speed AUX fan signal and topped off gas with duracool. It blows at 46F at the vents and only cost me $5 to fix.
Good luck
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Before you go through that, buy the $34 kit and see if it makes a difference.
Super easy and if mine craps out I'll still have to pay $400 or so the fix the whole system.
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Your not supposed to mix R12 and 134a. From what I understand it just screws things up.
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Your not supposed to mix R12 and 134a. From what I understand it just screws things up.
Correct. Most recommend a complete flush of the older R12 before converting it to the R134.
As for the o-rings/dryer, etc, I've done the R134 conversions on 2 past non-BMW cars using only the adapter/special oil and haven't had any issues with it for the few years I drove them.
The dryer is more of a wear item that can go bad if the AC was used often but doesn't have to be replaced if it's still good.
I do agree with the $30 route and trying that first. No sense in spending more than you have to, especially on our lower valued cars(relatively).
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I just said to hell with it.... took off compressor and pretty much everything related to a/c.... SO... My cars faster than yours.... because it weighs less.... :D oh, and it gets better gas mileage.... lol
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I'm too old for that $#@! now. I have a baby and a wife that both deserve cool air. :)
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I'm too old for that $#@! now. :)
Yeah me too. Instead I disturbed the weight bias a little by taking out the rear spare and speakers and going with a lighter battery. ;)
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oh yea.... well i have no spare, no trunk mat, no nothing back there really.... no back seat.... no sound deadning no power steering pump... my car is LIGHT.... lol... Engine mods are pricey. Taking things off is free.... lol :D I have another car if it gets to hot anyway...
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oh yea.... well i have no spare, no trunk mat, no nothing back there really.... no back seat.... no sound deadning no power steering pump... my car is LIGHT.... lol... Engine mods are pricey. Taking things off is free.... lol :D I have another car if it gets to hot anyway...
I live in the city where I have to parallel park everyday so I need the p.s. and the back seat for my occasional threesomes. ;) "Light" is a word I only associate with Lotus's and stripped out Honduhs.
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"Light" is a word I only associate with Lotus's and stripped out Honduhs.
Exaaaactly! I once was at an autocross where a guy had a brand new WRX completely stripped but for the driver seat and dash. It looked terrible in there and he was all proud of the stuff he'd taken out to "add lightness".
He spent the rest of the day trying to figure out how why all the other cars were beating him senseless.
He took a new car and made it into a loud, hot, bumpy ride with no place to set a drink... that still handled like piss.:rolleyes:
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Okay, I for one scan through some of the reading. Here's my two cents. If your a/c system has not been opened I mean broke a line or taken the compresson out and it is not cold. Have the system vacuum, the shop that will do it will tell you if there is a leak because they can't maintain the vacuum. Then get some oil, that should be the first thing you do. Because if you have negative vacuum the system will suck up that oil for the compresson. Then convert the system. Oh, I am taking all this from my personal experience. This 1991 318is A/C is cold even when the humidity in MD is 90% and heat inex is 105. By the way mixing the two R12 and R134 is not a doable.