[W126 Coupe] Air Conditioning Issues

[malcolm369 at comcast.net]

Hi Dick,

I too live in the greater  Boston area, and fortunately for me, have had a different experience than you in finding a shop with R-12.

I'm with you on the cooling ability of R-134.Years ago, during the mandatory changeover from R-12 to R-134, I both oversaw hundreds of R-134 retrofits, and the problems the manufacturer (Volvo) had due to the reduced cooling capacity of the new refrigerant. The new 240 series cars (factory R-134 filled) would not cool down, especially the 245 wagon due to the extra glass. It was so bad in fact, Volvo redesigned the heater to accommodate an updated evaporator - 20% larger, to deal with the problem. All this on a model slated to be dropped from the next year's product lineup.

On the retrofits, the A/Cs were more prone to leakage, as apparently the R-134 molecule is smaller than the R-12. I do not know if this (molecule size) is true, but that is what we were taught by Volvo. From personal experience with our 2 retrofitted 740 Volvos... there always seems to be some sort of A/C evac/recharge or repair on the horizon..

I too advocate with "go with what you can get..........", but personally I'd spend extra time/energy locating an R-12 savvy A/C specialist - if the car has yet to be converted. It will prove to be a chilling experience all around! :o)

In closing, once a system has been converted to R-134, it is not legal to reverse the process and go back to the 'nasty' stuff.


Looking forward to some SEC miles,    Malcolm

 -------------- Original message ----------------------
From: Dick Spellman <spell.yy at verizon.net>
> Hi Cal:
> 
> There remain HUGE proponents of R-12.  Obviously our MB systems were 
> designed for R-12 and will no doubt be happier if we continue to use 
> it.  R-134 presents higher head pressures and from the many complaints I 
> have heard on this and other lists, poorer quality cooling.  I've not 
> experienced a problem in any of the MB's I've converted and drive with 
> R-134.  However, I have experienced a really bad performance more than 
> once in rental cars or SUVs while traveling on business in the southern 
> US.  It has taken longer to demonstrate any cooling effect, longer to 
> cool down the passenger compartment and in one instance never cooled the 
> SUV in my opinion (the later was a Ford SUV POJ that I got stuck with 
> from Budget or whatever in Boca Raton, FL last July)  So, there is 
> plenty of evidence to support the fact that R-134 does not and can not 
> work as well as R-12.  But, where I sit in Boston there is ONLY R-134 
> readily available.  I am convinced that with the right set-up and care 
> in making the conversion you can be cool and quickly in a Mercedes.   I 
> have never experienced in a MB what I have so many times been dealt from 
> new car Mfg's poor quality in the rental cars I am saddled with driving.
> 
> So, go with what you can get (12 or 134) and hopefully you'll stay 
> cool.  I am fearless about recommending R-134 in Mercedes based on my 
> limited experience thus far.
> 
> Dick
> 
> malcolm369 at comcast.net wrote:
> 
> >Hi Cal,
> >
> >In addition to the other good advise posted, Here's what I did, finding a 
> leaking man/hose on a well functioning ACC.
> >
> >I did have the slightly leaking manifold hose replaced with OEM NOS (old 
> stock). The first one came through with rust inside one of the hoses. (1 day 
> extra) A fresh OEM hose was installed, along with new MB o-rings.... filled with 
> R12 (Cold) thank you.
> >
> >No drier/expansion valve, etc. replaced. ACC working fine & seemed a bit weak 
> only. The drier (in round numbers) will saturate in about 20 minutes with a hose 
> broken or unsecured. If the system is cool (or so) you're probably fine to leave 
> it alone. (seat of the pants prior A/C training & shop experience here) your 
> mileage may vary.
> >
> >OEM Part: $398.............  Aftermarket: $179!!!
> >
> >I don't know. If an aftermarket hose is designed for more modern R-134 
> refrigerant, won't it be better with the larger molecule R-12? I don't know.
> >
> >I think I'd replace it with an aftermarket hose today.
> >
> >The refrigrigerant & sundries are pretty standard......... the hose is the 
> biggie.  WOOF!
> >
> >Hope this is of assistance.
> >
> >MBL
> >
> > -------------- Original message ----------------------
> >From: "Calvin Young" <calvinyoung at cox.net>
> >  
> >
> >>My last visit to the dealer advised that my air conditioner manifold hose is
> >>leaking.  Anyone have  any experience with replacing this and want to share
> >>their experience.  How much is the hose, better to repair than replace,
> >>replace the receiver dryer at the same time, etc.
> >>
> >>Cal
> >>
> >>
> >>The MB Coupes Website!
> >>W126 SEC Mailing List
> >>Postings remain property of MB Coupes, L.L.C.
> >>    
> >>
> >
> >
> >The MB Coupes Website!
> >W126 SEC Mailing List
> >Postings remain property of MB Coupes, L.L.C.
> >
> >  
> >
> The MB Coupes Website!
> W126 SEC Mailing List
> Postings remain property of MB Coupes, L.L.C.