The Detailed E30 R-134a Conversion Thread/DIY

[jeffnhiscars]

Jay - Thanks for posting. I figured from your web site that the Seikos are junk and understand why you do not rebuild them.

I do have a follow-up question for the group: How difficult would it be to convert to one of the other compressors? The car in question is a 1988 320i Touring. I've never been clear on how BMW decided to put which compressor in which model. Are they like the style 5 wheels and sport seats - multiple manufacturers making the same part to the same spec? If so, do the different compressors mount to the engine the same and connect to the hoses the same? Please educate me.

Thanks, Cory

Basic primer on fitment ....aside from capacity, intended refrigerant and style (rotary or vane) compressors are spec'ed by mount type and hose position. When I did my cabrio conversion the mount I bought (which is now NLA)was set up for a specific Seltec model in to an e30 with a certain mount configuration. Because my also kit came with aluminum ferrules for the hoses I opted for a different model compressor that was the same shape and form but has an aluminum end plate so as to avoid dissimilar metals. The instructions advised rotating the hoses slightly at the compressor to clear the oil filter so this was a very specific application that worked out well.

When I converted my M10 car the mount was for a Sanden 508 with the 508 actually being the mount format rather than the compressor itself and the hoses were custom fabbed to fit.

The problem today is that no one makes a replacement mounting bracket so thats where you have to start. The OE bracket, to the best of my knowledge, will only allow you to mount OE style (meaning R12) compressors, which have proven to be adequate in many cases provided they have r134 seals, but are not designed to run at optimum pressure for r134. Trying to help but I may be raising more questions than Ive answered, but that IS the dilemma.

[cory58]

Basic primer on fitment ....aside from capacity, intended refrigerant and style (rotary or vane) compressors are spec'ed by mount type and hose position. When I did my cabrio conversion the mount I bought (which is now NLA)was set up for a specific Seltec model in to an e30 with a certain mount configuration. Because my also kit came with aluminum ferrules for the hoses I opted for a different model compressor that was the same shape and form but has an aluminum end plate so as to avoid dissimilar metals. The instructions advised rotating the hoses slightly at the compressor to clear the oil filter so this was a very specific application that worked out well.

When I converted my M10 car the mount was for a Sanden 508 with the 508 actually being the mount format rather than the compressor itself and the hoses were custom fabbed to fit.

The problem today is that no one makes a replacement mounting bracket so thats where you have to start. The OE bracket, to the best of my knowledge, will only allow you to mount OE style (meaning R12) compressors, which have proven to be adequate in many cases provided they have r134 seals, but are not designed to run at optimum pressure for r134. Trying to help but I may be raising more questions than Ive answered, but that IS the dilemma.

Thanks Jeff! Hope you're doing well. Great info as always. I do know that all the OE compressors were originally designed for R12. I'm not up for a custom mounting/hose project, so I'll just have to deal with the performance of an OE compressor. Since I need a new compressor and don't really want to buy a Seiko rebuilt at some unknown Chinese factory, I'm wondering if any of the other OE compressors (that can be rebuilt by someone I trust) are plug and play with the mounting bracket already in my car plus the new OE hoses I've purchased.

Cory

[ZeKahr]

I've never been clear on how BMW decided to put which compressor in which model. Are they like the style 5 wheels and sport seats - multiple manufacturers making the same part to the same spec? If so, do the different compressors mount to the engine the same and connect to the hoses the same? Please educate me.

Thanks, Cory

I think the early cars came with Bosch compressors and the later cars (like sometime around 89/90?) came with Seiko Seiki or Denso compressors.

[Hoffbrohaus]

Quick question. I am getting ready to have new lines fabricated to run to the compressor and condenser. Before I mount the new compressor do I need to fill it with PAG oil? Or is that something the AC shop can do after they put in the lines and I have them charge the system?

[jeffnhiscars]

Quick question. I am getting ready to have new lines fabricated to run to the compressor and condenser. Before I mount the new compressor do I need to fill it with PAG oil? Or is that something the AC shop can do after they put in the lines and I have them charge the system?

Your new compressor should indicate whether it is prefilled and how much oil it requires. Mine came w 150cc and the system requires I believe 250 so the rest can be distributed based on what was replaced. Ie for each new hose or drier add 10cc, condenser add 20 etc etc.. if you're having a shop do this they should know

[ejeffrey]

I have a question about the new pressure switch and receiver dryer. Is there an o-ring that is required when screwing in the pressure switch, or does this properly seal without one? I see an o-ring that fits, but I didn't feel it getting compressed when I tried it. Is there a different way to seal the switch and drier?

This is a fantastic thread - many thanks to the original poster and everyone else.

[ejeffrey]

I have a question about the new pressure switch and receiver dryer. Is there an o-ring that is required when screwing in the pressure switch, or does this properly seal without one? I see an o-ring that fits, but I didn't feel it getting compressed when I tried it. Is there a different way to seal the switch and drier?

This is a fantastic thread - many thanks to the original poster and everyone else.

After doing quite a bit of research on this, it seems that the o-ring needed is a 64-5-1-468-464 that sits on the lip just past the thread on the drier. Hope this helps others.

[oliviermorel]

New to this forum

After reading the numerous pages and post on this thread, I decided to convert to R134a (325i 10/1986 EURO the car is located in France). I am about to replace all the parts: hoses, expansion valve, condenser, etc.
My compressor is a Behr 70.623.04.512. This is where I am quite lost and don't know what path to take:
- should I rebuild mine (it is in very very bad shape!) ?
- buy the same model remanufactured with R134a seals ?
- looks like I could purchase a new efficient R134a compressor: any one could recommend brand / part number ? but I will have an issue with the mounting bracket correct ? did anyone built a custom bracket ?

Looking for advise.

Thank you!

[mlytle]

o-rings...
it appears many of the o-ring part numbers in the original post are now NLA. anyone found a kit or big box of misc o-rings that will do an E30?

[mlytle]

nevermind....looks like autohaus has them. FCP did not, nor did ECS.

[cory58]

New to this forum

After reading the numerous pages and post on this thread, I decided to convert to R134a (325i 10/1986 EURO the car is located in France). I am about to replace all the parts: hoses, expansion valve, condenser, etc.
My compressor is a Behr 70.623.04.512. This is where I am quite lost and don't know what path to take:
- should I rebuild mine (it is in very very bad shape!) ?
- buy the same model remanufactured with R134a seals ?
- looks like I could purchase a new efficient R134a compressor: any one could recommend brand / part number ? but I will have an issue with the mounting bracket correct ? did anyone built a custom bracket ?

Looking for advise.

Thank you!

There are no off-the-shelf brackets available to fit a modern compressor to an E30, so we all have the same conundrum. All the original compressors were designed for R12, making them less efficient with R134a. Fortunately for you, the Bosch/Behr compressor is a good candidate for rebuild (unlike the Sieko in my 1988 Touring). Take a look at post #599 in this thread. Jay Stratton (aka master6) rebuilds BMW compressors. He may not be a good option for you because he is in the USA, but if you follow the links to his web sites you will find lots of good E30 compressor info.

Others may disagree, but unless you can design and fabricate brackets for a modern compressor, I recommend that you stick with a rebuilt Bosch/Behr. Whether you rebuild yours or buy a rebuilt one is up to you. I personally wouldn't trust a rebuild from some nameless factory in China, so I found a company here in the USA to rebuild my compressor. Even though it is of inferior quality to the Bosch/Behr, it was working great before the seals started leaking.

Cory

[Tzantushka]

I'll add my recent experience here for those reading this thread.

Firstly 'hat tip' to jeffnhiscars and glucklich21 for sharing their insight and experience - very helpful.

My Bosch Behr compressor finally sh*t itself and leaked through the shaft seal after the A/C system was half converted to R134 in a previous life.
Lots of dead ends in re-building the original compressor, and lots of 'no call backs' from A/C shops as they don't want to touch these older systems.

After considering the risks with a re-built compressor - ended up doing it right and DIY-ing the conversion myself with a local A/C shop.

In summary:
- Existing evaporator flushed
- New R134a TX valve
- New receiver drier - I have 2x pressure switches (URO unit from Rock Auto)
- New parallel flow condenser (APDI 7013464 from Rock Auto)
- Stock aux fan refurbished
- Sanden SD5 compressor - SD5H14 - S6626 model variant (local auto A/C wholesaler here in Australia)
- LC Wylie M20 compressor bracket (facebook)
- Four Seasons R134a O Ring kit (Rock Auto) plus a few extra #6 O rings to replace o rings on the R134a ports
- Four Seasons High & low compressor lines (Rock Auto) - modified by a local A/C shop to suit the Sanden compressor
- Evaporator high & low lines converted to barrier hoses (local A/C shop)

End result is cold air (stationary in traffic or on the move), quieter smoother A/C operation and I'd say reduced load on the engine.

Full details in the build thread - but here's a quick engine bay pic

[cory58]

- LC Wylie M20 compressor bracket (facebook)

Wow - timing is everything! Finally broke down and sent out my Seiko for rebuild LAST WEEK, and now I find out LC Wylie is making M20 conversion brackets. I've always known about their M30 brackets but hadn't checked the FB page in a couple of years. Ugh!

Cory

[Caperix]

That bracket looks great, I wish I had known about it a few years ago when I replaced the Seiko compressor on my 91. Used a "new" rock auto one so I could keep the old one to look into rebuilding. It works good when moving but at idle in 90 degree weather the temp creeps up even with a parallel flow condenser & 16" spal pushed.

[jeffnhiscars]

That bracket looks great, I wish I had known about it a few years ago when I replaced the Seiko compressor on my 91. Used a "new" rock auto one so I could keep the old one to look into rebuilding. It works good when moving but at idle in 90 degree weather the temp creeps up even with a parallel flow condenser & 16" spal pushed.

Did you jump the resistor so the fan always runs on high ? The SPAL is fairly quiet so the sound shouldn't change much...just be sure to update the low speed fuse