The Detailed E30 R-134a Conversion Thread/DIY

[jrockbk]

So I did some reading and found some people who have r12 systems or converted r134a systems using r152a (PC duster cleaner) instead and claim great results with little to no modifications to the system other than a new dryer, and have most of the mineral oil replaced with POE oil and the system vacuumed that's it. No parts changed, no system flush, and the cans supposedly cost about $6 each, here is a link to what I found
http://www.stormfront.org/forum/t993641/
My question is has anyone in the e30 community tried this?
I want my a/c to work but I'm conflicted
Don't want to spend $300 or more on doing proper conversion nor do I want to spent the time, but don't want to buy some shitty autozone adapter, vacuum and refill with r134a to get 47F vent temps while going 50mph

[cavpilot]

Never mind. I figured it out.

[glucklich21]

Check your inbox.

[jd_e30]

Anyone?

[jd_e30]

I recently had my AC overhauled but have not been overly impressed with the AC temps. I did some research and found that the compressor installed on my car is listed as "non-compatible" on the BMW retrofit guide. I'm assuming it is an R12 compressor. My question is, what compressor should I swap to?

I came across this thread: http://www.r3vlimited.com/board/showthread.php?t=243751 and it looks like post #5 says it all. However, it looks like it took some custom work to make the lines work? What do you all recommend, short of spending $1200 on a new BMW compressor? Thanks for your help!

Additionally, since I have been using an R12 compressor, does this mean I need to vacuum the system and install a new dryer? What else might I need to install? All of these parts were replace during the recent overhaul, but I"m not sure how running an R12 compressor might or might not effect them. Please help!!

[MoreMayhem]

Sounds like a bad or worn out switch to me. Mine fails to 'latch' about 30% of the time and seems to be getting worse. Both the snowflake and recirculate buttons do this in mine.

[240trainee]

So I was playing around with the 91 318is I bought this past november. a/c system looks untouched. I was trying to figure out what all I need to get to convert this shit over.

The one question I have is this. when I hit the a/c button in the dash, it does not stay pressed. however, when I hold it I can hear the system pressurizing up in the dash. Which I am taking to mean the compressor isn't shot. I'll find out when I pull it off and empty it out...

does this mean the pressure switch is cutting it off? or a malfunction in the HVAC panel? I've never messed with a/c. I'll be bummed if I replace everything only to have a bum HVAC panel.

[JoeP]

If it came with r134 fittings from the factory I wonder if there is something internally different about the compressor. BMW did take the time to give it a new part number. RealOEM lists it as only r134. No reference to r12 like on the older compressors.

By the way, great DIY! Going to be doing the A/C on a 85 325e and was hoping to find something definitive about what parts to replace. Gotta keep the wife comfortable! Thank a lot!

[glucklich21]

Looking at RealOEM, beginning 3/92 the 325ic had a R134a compressor. Part number is
64 52 8 391 152. If that is an actual r134a compressor, it should fit M20 cars. Anyone know who manufactured it for BMW?

I believe Denso did. I've looked at a 93 cabrio's compressor and it looks the same as a normal M20 compressor. The only difference I noticed were the lines had the larger R-134a fittings from the factory.

[JoeP]

Looking at RealOEM, beginning 3/92 the 325ic had a R134a compressor. Part number is
64 52 8 391 152. If that is an actual r134a compressor, it should fit M20 cars. Anyone know who manufactured it for BMW?

[BMW B3 2.5]

Great write up

[MoreMayhem]

Congrats! I'm in the process of acquiring parts for this project in preparation for doing it myself. If you don't mind, which compressor did you go with?

Thanks!
I found an OEM one in the for sale section here on R3V that was said to have been rebuilt. A week in it seems to be holding up fine. It runs very quietly, but I don't know if that means anything. Just hope it continues to do so for a long time.

First day of hot weather here in So Cal, OBC said about 92 deg. It cooled okay when moving along at 65+ on the highway, not so good at stoplights. I think I'm going to have it evacuated and re filled at a different shop from who did it last. I think they filled it by the weight listed on the sticker in the engine bay. Guys in this thread say it should be filled by monitoring the high/low pressures and the vent temperature. Can't hurt to try.

-MM

[KAR]

Congrats! I'm in the process of acquiring parts for this project in preparation for doing it myself. If you don't mind, which compressor did you go with?

[MoreMayhem]

I just finished performing this operation on the patient below:



The only problem I encountered was with the pressure switch and the receiver/dryer.

I ordered the pressure switch suggested, part # 64538390971, and the receiver/dryer suggested, part # 64538391025.

This type of pressure switch threads onto the schrader valve (Hank?).

When I took the car to get charged with R-134, everything went fine until the A/C guy says "okay, turn on your A/C". The clutch didn't engage! Rather than pay him to figure it out, we jumped the compressor clutch from the battery and filled the system.

Once I got home I found that by bypassing the pressure switch the clutch would engage. Unthreaded the switch to look at it and didn't hear the little hiss of escaping refrigerant that I expected. That's because the pressure switch could never thread down far enough to engage the pin on the schrader valve. I ended up cutting a 2mm or so thick piece off the head of a finishing nail and gluing it to the pin inside the pressure switch. Now the systems works as it should.

I guess you're probably supposed to remove the schrader valve from the receiver/dryer before putting the pressure switch on. Since the system was already filled, there was no way for me to do that without releasing all the refrigerant.

On another note, replacing the compressor also solved a strange noise I was hearing at idle. Here's the old compressor:



"There's you're problem!"

Lastly, I'd like to thank Glucklich21, AutohausAZ, Google, Youtube...

[jeffnhiscars]

CPK should be paying me a commission :-)