After many years of development we have finally solved the W126 AC issue that the W126 suffers in 100f+ climates.
The solution is a bolt on P-flow condenser which still utilizes the stock condenser as a "pre-cooler". The stock condenser has inadequate surface area/air flow to completely condense R134 to a liquid state above 95f. The late model '85, split tube and fin condenser does a better job but is still lacking.
I had a custom P-flow condenser made that will fit snug in front of the stock cond. Freon flows thru stock then condenses completely to liquid in the P-flow filling the receiver/dryer with liquid. The aux fan and horn will need to be repositioned. Installation of the entire upgrade excluding proper evacuation and charging, will take less than 1 hour.
Vent temps are in the 36-40f range at idle in traffic. Compressor head pressures are reduced lowing HP requirement and extending compressor life.
No mods to the car are required and it can be put back to stock for the purist. My total parts cost is around $160.
Pics to follow...

Good call.

__________________
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!

Yep, It was 109f in the shade here the other day. My SD is black. not uncommon to see 145f interior temps.
The wife likes to drive a W126 as well. She does 100 mile commute every day thru Dallas traffic. Having to deal with that was motivating.

Excitedly waiting on pics...

yes, nuff talking, we need pics (and plans unless someone can fab some up)

Please post something soon. Up to 93 degrees outside my R134A system in my 86 sdl will put out 40 to 43 degrees from the vents. When it's 95 and above outside vent temps are on the order of 50-52 degrees. Over 100 outside and I am at 58 to 60 degrees.
I would be very interested in seeing this. I wonder if this is similar to the system that they make for the Porsche 911. The upgrade for it is a refrigerated dryer. I have seen them advertised in the Panorama.
I wonder if the " pro cooler" which I think it is called would work as a bolt on for our Benzs'.

__________________
John
1986 300sdl
1985 380se

I have to take pictures during the next install.

Things to note:

1) The system MUST be clean. Flush with every connection loose. Rinse with air, repeat (three times). If the residue coming out leaves a stain on white cloth, keep flushing.

2) Replace the receiver dryer.

3) Use the proper oil and amount. Double end capped PAG 150 is what is required for the R4 running R134, 6-8 oz distributed throughout the system. UV dye can be added for future troubleshooting if desired. Most R4 failures are due to improper oil viscosity. Also, Please see step 1.

4) Clean the old existing heat exchangers. The condenser is easy, the evaporator takes some effort but, it can be done working thru the HVAC fan housing with the fan removed. Brush the fins top to bottom, vacuum out the crud, flush with cleaner of choice and water. Remove the passenger side floor mat/carpet and be prepared to mop up what can't flow out condensate drain.
DO NOT BENT EVAP FINS!

5) Evacuate system on the hottest day possible while parked in the sun. This will ensure all moisture is removed. I like to let the pump run for at least 1-2 hrs.

6) Add R134 to Lo (suction side) port after purging hose of air. Heating the cans will help transfer. After second can (24oz) start watching the lo side pressure while measuring the temperature of the suction line near the fitting.(evap outlet) Compare temp/pressure to R134 chart. Wait five minutes with fan on auto mode. Continue to add small amounts of freon, wait five minutes to stabilize, until temps match chart. R134a Refrigerant Pressure Temperature Calculator 18-25psi is ideal and correlates to an evap temp of approx 19-30f.
At that time, depending on relative ambient humidity, you may begin to see frost on the return/suction line. Hi side pressure should be <200psi.
Do not depend on sight glass.

I'll try to get a more precise refrigerant amount needed next install I do.

Stay tuned... and cool.

Been there...

I did this very same retrofit on a 911SC Cabrio we used to have. This is very much like the 911 upgrade found here. AIR CONDITIONING HELP HOME PAGE,a/c,ac,air,air conditioning,barrier hose,Behr,Bosch,compressor,compressors,condensers,condenser,condensors,drier,driers,dryers,evaporato r,evaporators,freon,Griffiths,improvements,Kuehl,Nippondenso,Porsche,r12,r134a,San

Unfortunately, the W126 doesn't have the room for three or four condensers/fans.

It's all about taking the heat away folks.

Would this be something worth thinking about for people still using R12
or does the freon type even matter?

I've got a new PF condenser sitting around I could bolt on.

Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

Hmmm, makes me wonder what performance would be like with this setup with R12. I'm anxious to try this on a w123 and w124 as well.

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1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

I'm pretty sure there's not enough space on the W123. Grill is pretty close to the aux fan. Can't say re the W124.

Crap! Would have loved to rub it in a few faces around here locally, lol

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1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

With a 240D like mine without a fan clutch, where the fan is bolted direct, wouldn't there be less of a need for the aux fan? Or if it is needed, I would think a lower profile replacement could be fitted. I'll have to check it out.

__________________
1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D

I don't currently have a W123 to work with but lets not give up...

No way, not giving up. I have piles to W126's to play with, but if it's the holy grail, would like to figure out a way to provide it to the whole fleet, hehe. Anyway, going to sleep, and dreaming of low 20's at the vent making my hands ache on the steering wheel.

Take care,
Marc

__________________
1987 300SDL #1, 1987 300SDL #2, 1980 240D, 1982 300SD, 1994 S350, 1990 350SDL, 1991 350SD, 1985 300D, 2005 E320CDI

Gone, but not forgotten: 1981 300SD, 1982 300SD, 1987 300SDL, 1983 300TD, 1980 300CD, 1981 300SD #2, 1987 300D, 1987 300TDT, 1980 300D