Originally posted by spike68
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Spike, are you using the stock Bosch R12 unit for the conversion? I'm trying to figure out which compressor to buy for my update to R134a.
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Nice job! I'm glad everything worked out for you. I had no idea those compressors were so much different and its good to see you modified accordingly. Your system is definitely running a lot better than mine. I too followed that conversion write up, but my compressor just gave out. I'm not sure why, but I just used what I had. Will be swapping in another one this weekend. Hopefully I'll get tempatures like that as well.
Could I ask how much refrigerant you ended up having to put in the system total? And how much oil is your compressor recommended to use?
Could you also go into detail on the filling process? If you did it yourself...Leave a comment:
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Thanks for the write up. I've been researching as I need to get the AC working again. What model of compressor did you buy?Leave a comment:
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So the only thing I did not touch was the evaporator and the temp probe. It's all still installed. I was pretty surprised that the aux fan kicked on when hooking it up. Before I ripped out all my original AC gear- the aux fan wouldn't power up and I was afraid that I would have some sort of electrical issue to deal with. Fortunately for me- the old dryer switch wiring was all foobarred and that was the issue for no power to my old compressor.Originally posted by jeffnhiscars View Post
I did blow air into the evap unit to clean it out a bit but didn't remove it.Leave a comment:
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Based on the that reading you obviously got the job done very well. Fyi the evaporator temp probe, which I hope you reinstalled , is set to turn the compressor off at 37degree to prevent icingLeave a comment:
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A/C R12 to R134a using Sanden Compressor with stock M20 oil cooler lines
I just recently retrofitted a R134a Sanden A/C compressor into my '89 325i M20 with stock Oil Cooler lines. There is a bit of modification in order to make this work. But at the end- you will have a 100% R134a setup. There is a lot of broken information out there on the Sanden in the M20- threads started but never followed up with how it was done. Here is my contribution to the community...
First off- Big kudo's to Glucklich21's DIY on the conversion. There is a bunch of good info on his thread and a very nice writeup.
http://www.r3vlimited.com/board/showthread.php?t=246743
I found a Sanden R134a compressor out of a '91 e30 vert. I'm not sure if this was originally converted from r12 or was r134a from the factory. If you cannot find a used Sanden- they can be obtained NEW (not remanufactured) for under $200 on ebay. As mentioned before and in other threads- Sanden is an overall awesome compressor and is specifically made for r134a. Hearing the great reviews on it and rather than retrofitting my R12 Bosch, I decided to use it. It is super quiet and doesn't hog a lot of crank power.
Unfortunately, the mounting bracket that the Sanden uses is different than the stock R12 AC mount. I had to extensively modify the Sanden bracket to work. The mounting holes are the same on the block, but the CPS bracket and an ear on the block are in the way. Ended up using my Dremel and a grinding disk to make clearance on the bracket- along with grinding down the CPS bracket a bit.
This is what the Sanden bracket looks like (thanks member R3v Boris3)
You can try to make a bracket if you're up for the challenge:
http://www.bimmerforums.com/forum/sh...ressor-install
Then the Sanden IN/OUT fittings are in the rear of the unit- not in the center like the Bosh or OEM units. If you have a 325i or M20 with an oil cooler- you will have to modify your lines. No way around this- as the low pressure hose CAN fit- but rubs against the exhaust manifold/oil cooler lines.
I ended up getting mine re-done with barrier hoses. I added a hose from the front high pressure union to the compressor union (added about 5 inches in length for the curvature- removed the hard line sections and added two straight hose fittings to both ends. I would do a bend, something less than 90 Degrees for the condenser fitting) For the low pressure side, I had it shortened by 3 inches with a barrier hose. While the high pressure hose worked out perfectly, I should have removed only 2.5 or 2 inches from the low pressure hose, as it is a little too short and I need to figure out a good house mounting bracket- as in my pictures it is zip tied to the dizzy coil. I ended up having enough wiggle room to route them through the oil cooler lines. Wrapped them with exhaust wrap since I didn't want the rubber to get too hot and melt.
Vac'd my system down to 22mmHg with my crappy 5hp 20gal compressor for a good hour, added new PAG oil, a new parallel flow condenser from Amazon (the one pictured a few times in the R134a conversion thread) new aux fa wired to LOW, R134a expansion valve, new dryer with one pressure switch (modified from two switches) and of course new O-Rings.
Two pressure switch to One pressure switch wiring (the only straight forward way on the interwebs to wire this- the BMW TSB doesn't help out too well)
http://www.r3vlimited.com/board/showthread.php?t=342398
Blowing out a nice crisp 28 Degrees at idle on a 86 degree day at 50% humidity. The Sanden compressor is quiet as hell, can't even tell it is on (but it is!) It was a overall a giant pain in the butt project- but thankfully I didn't have any leaks or issues after getting everything squared away.
Sanden Bracket- modified
Routing of the AC lines through the oil cooler lines. I wrapped them with exhaust wrap I had laying around since I didn't want the rubber to melt being that close to the exhaust manifold.
The only pics I took of the modified lines. The high pressure side has that same fitting on both ends and only a rubber hose in-between (no hard lines)
PF condenser and new aux fan
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