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Re: Recent A/C and HFC134a Postings (kinda long)

I know it has been awhile since some of these have been posted, but I wanted
to offer some input.

At 10:12 PM 9/6/96 -0400, HoodsUp@domain.elided wrote in No. 197:
>Subject: <E30> Advice on AC Compressor Clutch - Urgent!
<snip>
>wouldnt run. It was then I noticed a mass of melted rubber goo oozing out of
>the compressor clutch/pully. Obviously its fried - but can the clutch/pully
>simply be replaced - does it just bolt on to the end of the compressor drive
>shaft. If thats the case It shouldnt be too expensive as I'm sure the rest of
<snip>

The clutch hub failed.  BMW does not service the hub separately.  I do not
think BMW services the clutch assembly separately, either.  This means you
will have to replace the compressor assembly.  Big $$$.  You may elect to
purchase a remanufactured unit.

At 02:42 PM 9/7/96 -0400, Marc Berger <marc@domain.elided> wrote in No. 199:
>Subject: <A/C> re: Any idea why my A/C is screeching?
<snip>
>twelfth summer of operation and it still blows cold as ever.  Am I lucky?
>Am I living on borrowed cold times till I have to replace my freon with the
>new stuff?  (Will I need to make repairs to use the new coolant or do I
>just shell out the big $ for old freon?  Is this a FAQ yet?)
<snip>
>1985 528e Bahama Beige 144K mi.

Yes, you are lucky.  To get 12 years of flawless service out of the Diesel
Kiki-Behr compressor that came on the 1985 528e is amazing.  You will not be
able to charge your system with HFC134a without changing the compressor
because the elastomer used in that compressor disintegrates when it comes in
contact with PAG lubricant and HFC134a.  And the HFC134a Seiko-Seiki unit
BMW sells is also quite expensive.  Wait until the compressor fails, then
retofit the system to HFC134a and use a Sanden SD508 or Diesel Kiki-Zexel
DKS14 with a new mount kit.

At 12:43 AM 9/10/96 -0400, DougS <dougs@domain.elided> wrote in No. 208:
>Subject: A/C
>
>Stick with the freon unit.  The new "environmentally safe" stuff they 
>using is actually more harmful to the atmosphere and doesn't cool nearly 
>as well and freon.  My friends with new cars have pathetic air 
>conditioners.
<snip>

I would be very interested to know where DougS gets his information about
HFC134a being more harmful to the atmosphere that CFC12.  Regarding
efficiency of HFC134a and CFC12 systems, there are many factors that go into
A/C system design.  I can sit you in a 1976 Corvette with the largest
passenger car compressor ever made and large condensor and an 1994
HFC134a-equiped 325i.  You will think the BMW blows colder air.  A
well-designed HFC134a system blows very cold air.  Period.

At 04:05 PM 9/10/96 -0400, GFOConnor@domain.elided wrote in No. 212:
>Subject: Re: A/C
<snip>
>Care to divulge your reference sources that define R134a to be more atmospheri
>c ozone damaging than R12, Doug?
>
>As someone who spent a few years with Nippondenso at the height of the
>changeover activity, I have my doubts about the severity of the entire
>ozone-depleting refrigerant issue, but this is certainly the first time I've
>heard that one. 
>
>Gerry O'Connor (sitting on an arsenal of 12 oz. R-12 cans... for ME only...no
>e-mail!)

Gerry and I are on the same page.

At 06:48 PM 9/10/96 -0400, henri baccouche <henri@domain.elided>
wrote in No. 213:
>Subject: AC seals maintenance
>
>Wait a minute....... nitrile / neoprene / nylon   O rings need nothing but
>a good interference fit in their fittings to seal. The part of the of the 
>O ring which is exposed to refrigerant/ lubricating oil is very small
>and  the refrigerant/oil does not  contact the whole sealing surface of
>the O ring. The modern  AC seals are also " inert" to the refrigerant and 
>lubricating oils. When the ac compressor crankshaft gets a wear groove
>from the seal,the compressor will leak refrigerant.
>The seals are so rugged that they actually cut grooves into the
>crankshaft.  There is no preventative maintenance for this IMHO.

Cycling the compresor in the winter to lubricate the shaft seal o-ring does
not require any human intervention.  In most of today's A/C systems, the
compressor cycles anytime you turn on the defroster.  If your A/C system
does not cycle the compressor during the defrost operation, manually
engaging the compressor in the winter to lubricate the shaft seal o-ring is
like eating chicken soup:  it wouldn't hurt (i.e. it is not proven to help
or hurt).

At 08:53 AM 9/11/96 -0400, R2002tii@domain.elided wrote in No. 215:
>Subject: RE: AC seals/r134a
>Nitrite o rings need oil to seal (even the green ones) your supposed to oil
>o-ring for ease of installation and proper sealing, the only thing I can
>think of that does not need oil is a sealing washer (I dont know if BMW uses
>'em tho). R134a works ok but because it runs at a higher pressure (and pag
>oil doesn't seem to be as good as the mineral oil) some wimpy compressors
>(like the one BMW uses) can't handle it but take a good compressor like a GM
>A6 and  a bigger condenser (to lower the pressure a bit) R134a seems to work
>great. Don't worry tho because there is a ton of R-12 around still.

BMW primarily uses compressors made by Nippondenso.  Nippondenso uses HNBR
shaft seal o-rings.  Nippondenso colors these HNBR o-rings green.  Only GM
products use sealing washer suction and discharge sealing materials (these
are made of neoprene, not HNBR).  GM shaft seal o-rings are also made of
neoprene and are colored blue or black.

Nippondenso compressors, whether they are used in BMWs, Mercs or Toyoyas are
generally as capable of pumping HFC134a as GM compressors (e.g. A6s, V5s,
HT6s, etc).  Compressors in HFC134a systems were designed to work with
higher pressures.  Most compressor manufacturers made changes to materials,
dimensions and function to handle these higher pressures.

Finally, there is NOT a <ton of R-12 around still> (see below).

At 12:21 PM 9/11/96 -0400, poffen@domain.elided (Russ Poffenberger)
wrote in No. 216:
>Subject: Re: A/C, R134a
>
>The R134a based A/C in my 1997 F150 cools much better than the A/C in my 1990
>325i. In fact, I dare to say it works better than any new car I have ever had.
>And it has a lot of volume to cool too (supercab).

Again, with a well-designed system, HFC134a-equiped vehicles blow cold air.

At 08:52 PM 9/11/96 -0400, "Dean.Schreier" <Dean.Schreier@domain.elided>
wrote in No. 219:
>Subject: RE:  AC Seals/r134a
>     If there is SO much R-12 still around, then why does it now cost about 
>     $25 a pound (about $100 to $125 to have one car recharged), and why is 
>     it currently the third most smuggled item across the border from 
>     Mexico (according to US Customs), next to Cocaine, and Marijuana???

This certainly puts the CFC12 issue in economic perspective.  Newsflash:
Don't plan on there being CFC12 next summer.  If there is, it will be
prohibitively expensive.  Stocks are dwindling fast.  Also newsworthy:
because contaminated CFC12 can be legally imported, individuals and
companies in foreign countries are taking virgin CFC12, dumping contaminants
into it and then importing it into the US.  Once it gets into the US, the
purchasers intend to recycle out the contaminants.  I would not want this
stuff anywhere near my car if I had a CFC12-equiped BMW.

Malcolm Davidow
Publisher
eAuto, LLC
eAuto (sm):  everything automotive (sm)
http://www.eauto.com/ (with plenty of BMW-related links)

1994 325is (current ride)
1984 325e (previous ride; retrofitted for HFC134a and 3.25:1 limited slip diff)