R12 - R134a conversion - A/C compressor - BMW M5 Forum and M6 Forums
E34 M5 Discussion 1988-1995 Sedan and Touring

  • 1 Post By pwalsh53
LinkBack Thread Tools Rate Thread Display Modes
post #1 of 2 Old 5th June 2013, 10:20 PM Thread Starter
Junior Member, warming up (<31 posts)
pwalsh53's Avatar
Join Date: Jun 2012
Location: Chicagoland
Posts: 23
Thanks: 1
Thanked 2 Times in 2 Posts
R12 - R134a conversion - A/C compressor

Hi all!

So I am in the process of upgrading to an R134a A/C system on my '91, and my car has a Bosch compressor (PN 64 52 1 385 416) that needs to be replaced. It is one of a couple of compressor part numbers that are unfortunately not compatible with R134a. There are some other threads in this forum that do a good job archiving this. The attached image is the list of part numbers that will NOT work with R134a, taken from the BMW service bulletin about retrofitting R134a (from 1996!). Hopefully this can be of some help as well!

I am posting because I am trying to figure out where I could get a remanufactured Seiko/Seiki compressor (PN 64 52 8 363 550) for less than the dealer's quote of $750. Part of that quote involves a ~$100 bracket that "may or may not be necessary." This statement agrees with what I have found on these and other forums about Seiko/Bosch compressors and which engines they fit on with/without brackets. Bav Auto has a reman compressor for $800 but does not match the part number, and there is no mention of a bracket.

Apart from doing a junk yard search on car-part.com, does anyone have any positive experiences here? The labor for the conversion is already going to be pretty high, so if I can avoid any part cost markup, that would be a pretty big help. But at the same time, I want to do it right. I am thinking about the longevity of this fine hand-built beast, and don't want to half-*** anything. You just don't do that to an M5 :-)

Attached Images
pwalsh53 is offline  
Sponsored Links
post #2 of 2 Old 14th June 2013, 10:14 AM
Alan Archer
m5board.comoholic (>1000 posts)
Alan Archer's Avatar
Join Date: Jul 2000
Location: London,United Kingdom
Age: 44
Posts: 1,298
Thanks: 41
Thanked 100 Times in 72 Posts
I've always used a very knowledgeable A/C guy for the cars in my family.
Every visit he would show me A/C units, cars and compressors in various states of undress.

He's retired now, but we spoke a few times about the swap from R12 to R134 a.
He used to do conversions for customers who would bring him a "kit" consisting of a bunch
Of o-rings to replace and not much else.

We both understood the potential for o-ring system seals to react to the change & he listed
The merits of replacing the receiver/dryer unit when upgrading.
But I don't ever recall him having compressor issues.

Infact he told me that on some very old motors he simply took a deep breath & gassed them up with 134.

If I were in your shoes I would be tempted to do the same.
The worse senario is that your system leaks and you have to then strip/fix it, in which case you're back where you are now.

But worth a shot I think.



///M5 the only substitute for capacity is even greater capacity...

Alan Archer is offline  


Quick Reply

Register Now

In order to be able to post messages on the BMW M5 Forum and M6 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes Rate This Thread
Linear Mode Linear Mode
Rate This Thread:

Similar Threads
Thread Thread Starter Forum Replies Last Post
AC Compressor lifespan getbent E39 M5 and E52 Z8 Discussion 24 28th December 2013 08:35 PM
R12 to 134a A/C Conversaion SHkarus E34 M5 Discussion 2 19th July 2011 06:38 PM
A/C R134a Help mdyaman E60 M5 and E61 M5 Touring Discussion 1 3rd July 2010 08:56 AM
02 M5 - A/C Compressor Whine? britm3 E39 M5 and E52 Z8 Discussion 0 3rd July 2007 06:11 PM
AC compressor Need help!! WylM5 E34 M5 Discussion 3 28th October 2003 07:48 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome