J,

It is a bad deal. If there was any R12 in it, the R134a mixed into it made a toxic gas. Under the right conditions (and it's not too far to get there) that makes phosgene - WWI chemical warfare agent!

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Yeah "auto" usually just runs at a medium speed in my car.

__________________
1981 300SD 512k OM603

You're actually experiencing the "auto" function

If you push the center automatic button in notice how it releases the top or lower button depending which one has been pressed.

There isn't any hardware behind the auto button.


Only half correct When r12 burns it creates phosgene gas. Mixing r12 and r134a won't do anything since the atomic structures of the two chemicals are stable. It will probably just destroy the compressor since the oil will be all sorts of screwed up which is sad in the same way that phosgene is dangerous!

Here's the formula for stoichiometric equation where O2 is atmospheric oxygen and the catalyst is a flame.

CCl2F2 + O2 -> F2 + CCl2O

__________________
-Typos courtesy of my mobile phone.

To: all who read this NEVER MIX R12 with R134a

There need not be an open flame to form phosgene. R 12 doesn't 'burn' but as I described, "under the right conditions" in the presence of heat -{straight from the EPA test} "From an electric motor or hot metal surface." There need not be an open flame to form phosgene -{straight from the EPA test} "The chemicals that result under these circumstances always include hydrofluoric acid (HF). If the compound contains chlorine, hydrochloric acid (HCl) will also be formed and if source of water or oxygen are present phosgene will be formed." Water and oxygen are in the category of 'non-condensables' and are always present in any system in small amounts, large amounts if the system was not evacuated.

NO SIR, - Neither are stable (however R134a is much less unstable than R12.) Chemical reactivity is why R12 is no longer being manufactured and R134a should NEVER BE MIXED with any chlorofluorocarbon. I'm not trying to pick a fight here but did you actually take the 609 test?

Any technician mixing the two or transporting improperly mixed refrigerants is subject to a $25,000 fine and up to five years imprisonment. [This] also violates OSHA workplace regulations and may also violate state laws-EPA

Heat does speed things along but it's not really a substance IE: catalyst BUT in the right mixtures, passing the gas through a 450F pipe is one of the ways phosgene is made commercially (for pesticide and plastics production.)

But we do need to account for water since we're making HCl and HF..

CCl2F2 + H2O -> 2HCl + 2HF + CO
Instead of a string of equations (did enough of that in school, and oddly enough-work) the products include CO, CO2, phosgene and a literal "stew" of chemicals, some toxic - some not.



To: all who read this: NEVER MIX R12 with R134a

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

The original post, was regarding a 124, which does have a switch behind the auto button, and the auto button does latch.

__________________

Gone to the dark side

- Jeff

Yes there is and it works great, it took me sometime to figure it out also but it is nice.

Mine does the same thing with the auto button clicked in as it does with none of the three buttons clicked in. The "auto" function.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

On my 83 I plan on adding an infinitely variable speed control to the list of things to do. Not difficult: a power transistor and a potentionmeter and wire it up.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Quote about mixing R12 & R134a from a freon designer:

Posted by George Goble on June 19, 1999 at 21:14:44:
In Reply to: Re: Replacement of R12 with R406a posted by John Strauss on June 16, 1999 at 16:07:09:
As you stated, the EPA has now made it "illegal" to mix
different refrigerants in cars.. Last time I looked, it was
still legal to mix 'em in stationary equipment.
R-406A in various mixtures with R-12 were run in a fleet of Humvees
early on (ambulance bodies).. R-406A by itself gives a 6-8F colder
duct temps than R-12, so with 50/50 R-12/R-406A the performance
gain was about 3-4F or 1/2 of using pure R-406A. (before EPA mixing
ban).
The "shocker" in illegal mixing is that mixing Freeze12, FR-12,
or just R-134a with R-12 (computer simulation on what happens)
start out with one slowly leaking R-12 system, gets down to about
50% remaining charge when the owner decides a recharge is needed.
1) Assume owner just "tops off" with R-134a (system has mineral
oil that R-134a will not "carry", but 50% R-12 remains, so oil
return to the compressor works fine. R-134a and R-12 form an
"azeotrope" with a boiling point of around -31F (R12 is -21.7F,
(R-134a is -14.7F, Freeze12 is around -8F) at 1 ATM. This
results in a performance improvment (capacity increase 25% or so)
along with slightly higher head pressures.. Performance gain
(over R-12) is about 2/3 of the gain of using 100% R-406A.
Freeze12 (80% 134a/20% 142b) is similar, except 2-3F warmer
than the above.. still much better than total R-12. This
"good performaning" mixture is called "contamination" by those
with vested interests in preventing it.
2) Next summer, system low again, user tops it off with R-134a,
now there is 25% R-12 (still enough to carry oil fine) and
cooling is still better than R-134a.
3) 3rd summer.. system low again.. tops off again with R-134a,
12.5% R-12 remaining.. still returns mineral oil fine.. cooling
now is about R-12 performance..
4) 4th summer...system low again.. tops off again with R-134a..
about 6% R-12 left, marginal mineral return, but probably
will work.. R-134a cooling performance..
5) 5th summmer.. top off again.. 3% R-12 left.. oil fails to return
compressor siezes up and fails.. IF using Freeze12 instead,
performance will be about +15F warmer than R-406A (autofrost)
Look how well this "illegal contaminated system" worked.
Now if legal...
1) remove all R-12.. charge with R-134a or Freeze12..
and dont change the oil to POE.. (still is mineral).
performance: lower, 134a vs R-12..maybe 10F warmer..
If R-134a in mineral oil, compressor will fail within
1 week (or may go a couple of years if oil was changed to POE).
Freeze12 in mineral oil may run 3-4 months before compressor
gets "dry" enough to fail.
Doing things EPA legal is a "bad deal" when doing a "proper"
conversion to R-134a or Freeze12.. Illegal topping off gets much
better performance and 5 years of runtime...
go figure..
--ghg, inventor of R-406A (autofrost) and R-414A (GHG-X4)

Hmmmm.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

George Goble is my hero. Have you ever seen the video of him "lighting" a charcoal grille with LOX? Epic. Not your typical Purdue prof.

http://en.wikipedia.org/wiki/George_H._Goble

scroll down here for the only links I still have: http://web.archive.org/web/20021003203611/ghg.ecn.purdue.edu/~ghg/

__________________

Gone to the dark side

- Jeff