R12 To R134a Conversion - BMW Forum

viali8 · 07-26-2005, 09:29 PM

Just wondering if anyone has done the r12 to r134a conversion for their ac. is it a do it yourself job or is it very difficult. Do you need to buy a new compressor if you switch to r134a? where is the best place to buy a conversion kit? any help is greatly appreciated. thanks

sp0rky · 07-26-2005, 09:42 PM

The kits at the stores claim you dont need to change any parts at all - just get your R12 evacuated and vacuumed (free from AC shop because they re-sell R12)

However, I don't see how that is RELIABLY (long term) possible.

Either way - those kits are sold at Wal Mart, Kragen, Target, etc...

Generally, you have the R12 evacuated and vacuumed - then flushed - then replace the reciever dryer and seal it all back up and leak test it. Vacuum again and recharge with R134 and compatible oils. Thats the PROPER way to do things.

Changing of the o-rings, etc is usually not necessary (myth) unless yours are cracked, etc.

kawasabi · 07-26-2005, 10:59 PM

Quote:

Originally posted by sp0rky@Jul 26 2005, 08:42 PM
The kits at the stores claim you dont need to change any parts at all - just get your R12 evacuated and vacuumed (free from AC shop because they re-sell R12)

However, I don't see how that is RELIABLY (long term) possible.

Either way - those kits are sold at Wal Mart, Kragen, Target, etc...

Generally, you have the R12 evacuated and vacuumed - then flushed - then replace the reciever dryer and seal it all back up and leak test it. Vacuum again and recharge with R134 and compatible oils. Thats the PROPER way to do things.

Changing of the o-rings, etc is usually not necessary (myth) unless yours are cracked, etc.

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I did it and the proper way to do it is to replace the dryer and the expansion valve. The AC in my E30 is COLD and the expansion valve did the trick. It is easy to change also, just take out the glove box and that side panel and its right there.

Hypnogaja · 07-27-2005, 04:21 AM

Check out my previous post

Still working great!

Trob · 07-27-2005, 07:36 AM

My brother in law and I both just used the walmart "death kit" and after a year of use nither one of us is having a problem!

325eXTATIC · 07-27-2005, 10:41 AM

okay, I know that later e30's are ready to simply do the swap as you have laid out, but what I have read is that earlier e30's compressors are NOT compatible with R134. Is this true? if you go to bavarian auto (bavauto.com) they show a compressor and rebuild kit for almost $1000. I understand most of that is the cost of the compressor itself, but I have found new old stock R12 compressors on a few websites for under $300, what gives?

Will this rebuild as you have described it work on my old '86 325e?

Thanks all!

Josh W.
'86 325e w/Dinan ECU

sp0rky · 07-27-2005, 01:52 PM

The cost of R12 is around $400 / lb in my area .. I don't know about yours
so If you buy an R12 compressor because it's cheap , having it refilled will far exceed the cost of the 134a system. You need 4.5lbs of refrigerant.

R134a is roughly 9$ per lb.

I dont know why the cost difference between compressors is so huge, though.

And yes - expansion valves sometimes need replacing if they are sticky - but a proper AC flush should eliminate the need for a new one if it's already in good condition.

kawasabi · 07-31-2005, 10:36 PM

Quote:

Originally posted by sp0rky@Jul 27 2005, 12:52 PM
The cost of R12 is around $400 / lb in my area .. I don't know about yours
so If you buy an R12 compressor because it's cheap , having it refilled will far exceed the cost of the 134a system. You need 4.5lbs of refrigerant.

R134a is roughly 9$ per lb.

I dont know why the cost difference between compressors is so huge, though.

And yes - expansion valves sometimes need replacing if they are sticky - but a proper AC flush should eliminate the need for a new one if it's already in good condition.

[snapback]365494[/snapback]

Well, the expansion valve i put in the car was stamped R134A and the one I took out was stamped R12. I made a huge difference in the performance of the system.

e36_m3_Turbo · 07-31-2005, 11:42 PM

r12 is harmful to the o-zone.

triggrhaapi · 08-01-2005, 05:12 AM

It is indeed true that older R12 compressors are not compatible, but you can have one rebuilt to work (I think the impeller and oil weight is different and that's about it) for cheaper than a new 134a replacement unless of course you find a used R134a one laying about.

Hypnogaja · 08-01-2005, 05:34 AM

The rubber elastomer is what falls apart in the older R12 Bosch compressors because PAG and POE oils are slightly acidic.

I know that the rebuilt ones that they sell at Autozone and Advance have new neoprene seals in them that do not degrade after a retrofit.

ldsbeaker · 08-01-2005, 05:03 PM

So what you're saying is that I go to Autozone, ask for a compressor for '86 BMW 325es, and they will bring me this Bosch reman. unit?

kawasabi · 08-01-2005, 06:07 PM

Quote:

Originally posted by ldsbeaker@Aug 1 2005, 04:03 PM
So what you're saying is that I go to Autozone, ask for a compressor for '86 BMW 325es, and they will bring me this Bosch reman. unit?

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Any airconditioning parts you purchase as a new part and NOT old stock will be automatically R134A compatible. They don't make parts to be compatible with R12 anymore.

Hypnogaja · 08-02-2005, 11:45 PM

you need to specify whether your compressor is a Bosch or Seiko-Seiki unit.

The japanese compressors are compatible w/ R134a, but i'd look into getting a new one anyways. It's almost 20yrs old and depending how long the system has been non-functional, the compressor might be bad from going dry.

If it's a Bosch compressor you need to replace it with a remanufactured one from Autozone or Advance.

R134 will destroy yours within a few days if you just convert it over with a death kit. (I learned that the hard way

)

AFAIK, you cannot swap Seiko to Bosch or vice-versa.

Compressor list

race01 · 08-04-2005, 07:32 AM

Quote:

Originally posted by viali8@Jul 26 2005, 09:29 PM
Just wondering if anyone has done the r12 to r134a conversion for their ac. is it a do it yourself job or is it very difficult. Do you need to buy a new compressor if you switch to r134a? where is the best place to buy a conversion kit? any help is greatly appreciated. thanks

[snapback]365380[/snapback]

My 87 325e system was completely empty of R12. We just vacuumed it down to be sure and then added R134A. You might need to add a little of the oil for the 134. You might have to replace "O" rings, but that is common. They dry rot. That's it. Mine works fine, although it leaks out in the winter. No problem, we just add a can or 2 in the summer and stay cool. They used to act like it was a big deal, but we did it on quite a few of our vehicles, and they are fine.