Air Conditioning options

[Alex Mc]

My M20-powered 318is is very much in need of a chilly cabin during the summer months here in North Carolina, but the previous owner decided to forgo this option when he swapped the engine in a few years back.

Is my only option to purchase a R134 compressor and begin the conversion process or is running a R12 system still viable? There is plenty of access to R12 cannisters on eBay, but is this a fool's errand? Bunged second-hand compressors change hands for little money and I wouldn't have to replumb everything for R134.

The R134 route seems very pricey in comparison with compressors alone costing nearly half a G.

Thoughts? Experiences?

[bmw325csi]

A lot of people don't change out the compressor and still run r134 with no issues. I did on my last car. Ac worked well for the 2 years I used it

[997_rich]

all the seals are probably shot on all your R12 plumbing anyway. Whenever I've gotten into these r12 projects, I end up replacing half the parts anyway. So, recommending you just go R134a. That way you won't have to beg borrow and steal for R12 in the coming years.

[jlevie]

To wind up with a reliable AC system you usually wind up replacing all of the o-rings & soft lines as well as the expansion valve and dryer. Then you hope that neither the evaporator nor the condenser have leaks. And of course you need a compressor. At that point you have a system that is fully R134A compatible since the R12 only parts aren't available. So you might as well use R134a and not pay the premium for R12.

On my restoration car I replaced everything except the all metal lines. With the exception of the condenser I used BMW parts. For the condenser I used a parallel flow unit to compensate for the loss of performance of R134a in a system sized for R12. All told, the parts were roughly $1500.

[Alex Mc]

Jim, I understand that R134A operates at higher pressure/temps than R12 and therefore the higher flow condenser is ideal, but is the OEM condenser insufficient?

It's not that I'm trying to cut corners, but I don't need a full-on new specification system either.

[gtdragon980]

I think I screwed my a/c system up because I threw R134a into my R12 system without knowing. I had a sticker saying r134a retrofitted on my grill, but later found out the grill was swapped. I'm currently trying to figure out how bad I fucked it up!

[funcrew]

Not to be emo, but: http://www.e30tech.com/forum/showthread.php?t=113435

[jlevie]

Jim, I understand that R134A operates at higher pressure/temps than R12 and therefore the higher flow condenser is ideal, but is the OEM condenser insufficient?

It's not that I'm trying to cut corners, but I don't need a full-on new specification system either.

The thermodynamics of R134a re different. Ideally you need a larger evaporator and condenser for best performance. But these cars can't accept what you really should have. A decent compromise is to replace the serpentine condenser with one that has parallel flow (~$125 as I recall). Not really a major expense.

[jeffnhiscars]

According to the factory R134 retrofit bulletin, the following left the factory with compressors that are not R134 compatible:

318i from 7/85-8/85
325e, 325i, 325iC from 7/87 - 10/88
325iX, M3 ALL

This means if you have a good compressor running R12 and your car was not made during the above timelines, it is suitable for R134a.

[Alex Mc]

According to the factory R134 retrofit bulletin, the following left the factory with compressors that are not R134 compatible:

318i from 7/85-8/85
325e, 325i, 325iC from 7/87 - 10/88
325iX, M3 ALL

This means if you have a good compressor running R12 and your car was not made during the above timelines, it is suitable for R134a.

While this is interesting, it is irrelevant in my case unless it is acceptable to run a used compressor. Is this worth trying a second hand unit? There are "inspected" units on ebay for small coin.

[jeffnhiscars]

While this is interesting, it is irrelevant in my case unless it is acceptable to run a used compressor. Is this worth trying a second hand unit? There are "inspected" units on ebay for small coin.

Its relevant since it also lists the SN's for suitable Bosch compressors to swap in. I cant post the pdf but this is from Pelicans article on the subject:


The E30 cars are a little more difficult, as almost all of them were fitted with R12 systems. A detailed BMW Tech Bulletin covers the R12 to R134a conversion (BMW Document # 64 05 96). The E30 cars with compressors that are not compatible with R134a include the 318i (July 1985–August 1985); the 325e, 325i, and 325iC (July 1987–October 1988); the 325iX; and the M3. You should check the part number on your compressor prior to the upgrade to make sure that it is compatible with R134a.The following table shows a list of compressors that are not compatible with R134a. You should replace these compressors with part number 64-52-8-363-550.

64 52 1 377 944

64 52 1 377 947

64 52 1 385 416

64 52 1 385 930

64 52 1 386 411

64 52 1 377 940*

64 52 1 377 941*

64 52 1 377 943*

64 52 1 377 946*

*Requires clutch wiring adapter P/N 64-52-1-386-224


If your E30 has an R134a-compatible compressor, or if you purchase the upgraded one, all you need is the E30 R134a retrofit kit. Like the E36 kit, it contains a new receiver drier, new O-rings, a capacity label, and a set of R134a valve adapters (part number 82-31-9-067-394). If your compressor is low on oil, you will also need PAG compressor oil (part number 82-11-1-468-042).

The full article is here>

http://www.pelicanparts.com/BMW/techarticles/101-Projects-97-AC/101-Projects-97-AC.htm

GL

[Alex Mc]

Excellent point Jeff, I assumed everything was now r134a compatible.

Regarding compressors, is there anything in the Auto Zone / Advance Auto Parts world that is a viable alternative to a $500 unit from Pelican? Again, trying to keep an eye on costs.

Also, what is the consensus on used compressors?

[jeffnhiscars]

Personally, I think this is too much work and expense to mess around with a compressor of unknown origin and Im sure you realize that "inspected" doesnt mean much. I may be doing a retro on my barn find if an r12 top up doesnt get it working so I may be in the same boat.

These guys are a good reference and if you do a websearch using the PN's there are numerous sources. I used a Sanden 508 rotary last time and a mounting adaptor kit both of which I paid under $300 for. Seems to me Ive seen the compressors for $225ish and the results were colder AC than my new 911 had.

http://www.polarbearinc.com/PBPC/Homepage/Search/Co/CO_BMW.html#Anchor-325ic