[W126 Coupe] A/C Not cooling

[Michael Ramay]

Excellent discussions by Gary and Dick!!

I took the AC system apart on my 560SEC, replaced all o-rings, flushed it,
new synthetic lubricant, and then filled it with propane (R290). That one
gives me 39F air out of the vents on a 105F Las Vegas day. It does not cool
that well sitting still, but it's acceptable. Any movement in traffic and it
cools right back down to 45F to 50F air.

My 560SEL had been converted to R134 and as Gary states, it doesn't cool as
well as the SEC. That said, I put a dual electric fan setup on the radiator
in place of the engine driven fan (with a new 140-amp alternator to handle
that extra electrical draw) and that made a BIG difference in the cooling.
That car cools well sitting still and very good while moving. That said,
this winter I'm going to replace all o-rings, flush the system, and change
it back to R12 fittings and a propane fill.

Mike
In HOT Las Vegas

On Sun, Aug 14, 2011 at 10:39 AM, Gerry Van Zandt <gerryvz at me.com> wrote:


> If your A/C system was just the stock R12 system that was converted over to

> R-134a, it will NEVER cool more than about 60% as well as the R12 system did

> UNLESS (as Dick explained) key components of the system are changed over to

> those that are optimized to work with R-134a.  R-134a requires a different

> set of parameters to work at its best and this is just not possible with a

> stock R12 system that has been emptied, new fittings installed, and filled

> with R-134a and compatible oil.

>

> Dick did it right as he explained it, and thus is getting excellent

> results.  On the other hand, I had my system on my 1989 560SEC converted to

> 134a about 2001.  When I lived in Portland Oregon, where the temps rarely

> get above 85F in the summer, the 134a system (with its reduced capacity)

> worked just fine as long as the refrigerant level was up to the correct

> level.  However, since moving to Houston 3 years ago, I've found that my

> 134a system is pretty miserable in the summer heat.

>

> My system is in tip-top condition (no major leaks, and all key components

> in good operating condition, though they are the stock R12 components) and

> it only works decently when the car is moving in traffic.  Over long

> interstate trips (say from driving from Houston to Dallas) at high speeds it

> works quite well.  Never ice cold but will get the car down to a very

> comfortable/cool temperature.

>

> I find the same thing as well -- below temps of about 80-85F outside, the

> converted system actually works quite well.

>

> However in stop and go traffic, it's miserable and pretty much just blows

> warm air after a minute or so of being stopped.  I'm actually preparing to

> change my system BACK to R12 this winter -- my home A/C guy just sold me a

> left-over tank of about 15 pounds of R12 (for $50) that he's had sitting

> around for the past 15 years and not using.  I'll have my indy shop test my

> system for leaks, replace any components that need it, and have the R-134a

> removed & then the system cleaned out several times with solvent, R-134a

> fittings removed, and having new oil and R12 introduced back into the

> system.  Not an easy retrofit, but I can't handle another summer of only

> mediocre cooling.  My 1987 560SL (still on R12) is excellent in all

> conditions.

>

> The bottom line is that you'll never get good efficiency from an R-134a

> conversion (from an R12 system) unless key components are replaced.  Systems

> designed specfically for R-134a (such as that on my 1994 E500 W124) work

> very very well (though still not quite as good as an R12 system, IMHO).

>  It's 96F outside and I just got home from downtown Houston (30 miles away)

> and was nice and chilly in my E500 all the way up I-45.

>

> It's a serious consideration for those with R12 systems that have been

> converted to R-134a, to change them back now that the price of R12 has come

> WAY WAY down and the price of R-134a has gone up.  The difference in

> efficiency is truly worth making it worth considering.

>

> My two cents.

>

> Cheers,

> Gerry

>

>

>

>

> On Aug 14, 2011, at 11:15 AM, mbcoupes-request at mbcoupes.com wrote:

>

> Message: 6

> Date: Sun, 14 Aug 2011 08:22:36 +0400

> From: Yousef <usef4188 at gmail.com>

> Subject: Re: [W126 Coupe] A/C Not cooling

> To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>

> Message-ID: <A5B63E26-49EA-408A-9634-0A612B4719A2 at gmail.com>

>

> Content-Type: text/plain; charset="us-ascii"

>

> Yup runnin at 134a..

>

> Sent from my iPhone

>

> On Aug 14, 2011, at 2:00 AM, Jonathan Hodgman <jhodgman at gmail.com> wrote:

>

> ya'll running R134a??

>

>

>

>

> The MB Coupes Website!

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> Postings remain property of MB Coupes, L.L.C.

>




-- 
Mike Ramay
cell: (702) 494-8056
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