Sholin, I am sticking with R12.... and I think the combo TX valve MB uses purpose is to keep the refrigerant from making the evaporator too cold... to keep it at above 32 degrees to so that moisture will not freeze on its fins and stop flow through it...
From what I have read TX valves are much superior to other types of systems , so I am glad we have them on our cars...
I am going to go with Parallel Condensor and strong fan... and will add a filter between the compressor and the new Condensor....

leathermang,

Please keep us up to date on your a/c upgrades. As it stands now, I've got a functioning 134 system, but it doesn't provide anywhere near enough cooling with the outside temps > 90. I may do what you are doing: upgrade to parallel flow condensor, add electric fans (remove existing engine fan), convert back to R12.

Sholin

__________________
What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.

Just for kicks, here's a link to some who did a parallel condens conversion on a Jag:

jag conversion

__________________
What else, '73 MB 280 SEL (Lt Blue)
Daily driver: '84 190D 2.2 5 spd.

I only looked at the project to install a new Parallel Condensor... but it was great.... pictures and info right on the money.. thanks for posting that url....

I noted early in this thread someone mentioned that the 10P15C compressor may not be big enough to do the cooling that they wanted. I do not know if I agree with that. Nevertheless, Denso does make the 10P17C compressors which are the same design but a bigger displacement. Some of you may want to check to see if the 10P17C would work on your cars in place of the 10P15C. If anyone knows for sure let us all know please.

For those who are electing to stay with R-12 I think that is the way to go for those cars that came with R-12. I believe the R-134a conversions have a greater chance of damage to compressor and components as many don't do the best job of flushing and evacuation of the system. For example if I'm looking at an earlier w124 model that came with R-12 and has been converted to R-134a I going to wonder if you have some acid in the system that is about to cause a leak in the evaporator ! !

I would just feel better about a w124 that still was using R-12.

James

__________________
JD

What I am pretty sure about now is this.... just about any size auto ac compressor working correctly will do the job.

The bottle neck in terms of the physics is THE AMOUNT OF AIR FLOW ACROSS THE CONDENSOR.

So getting the best aux fan you can afford and being sure it comes on at the right times is the basis for increasing reserve ( idle in a hot climate ) ability of your air conditioner. This assumes that the rest of the system is operating normally.

I live in saudi arabia.. very hott here..it aint summer if the temps are not 42+ degree celcius

SOLUTION 1:


throwin in 2 reciver/dryer would strain the compressor.. rather just install a bigger R/D but keep it limited to ONE only

get parallel flow condenser with he biggest size and thickness u can fit in..

stick to R12

get rid of the engine mechanical fan.. i swapped in an electrical fan from Chrysler 300C V8... it has a bosch dual speed motor and blows really strong air

connected with the compressor cluth via relay.. the fan automatically spins at higher speed when compressor is engaged along with the benz orignal aux fan...the car just sounds like a jet engine.. too loud if u are driving with open windows and AC on

SOlUTION 2:

Install a 5 gallon cubical water canister with tight lid and imersible water pump in ur trunk.. route the hoses under the car and set up a system to spray fine mist of water right on the spinning aux fan.. set up the required electrical and a switch on a dash.. now everytime u get stuck in traffic and vent dont blow enough cold air.. press the switch and the condensor temps will go down fast,..the gast high pressur will fall.. and really cold air will start to blow....

i tried both setups in real.. the second one when i didnt had enough cash to go with the first one.. they both worked well but the second one beats all since evaporation carries away heat faster.. execpt for the extra weight of 5gallon water canister in the trunk

"throwin in 2 reciver/dryer would strain the compressor.. rather just install a bigger R/D but keep it limited to ONE only"--theboss

In my car there is a flat unused space on the same plane which the original R/D sits.... What makes you think the physics of one larger R/D is different from say two normal size R/D's ? Lets assume the larger one is twice the capacity of the original one for discussion purposes....

"get parallel flow condenser with he biggest size and thickness u can fit in.."
No question about that one...

"stick to R12"
No question about that one...

"get rid of the engine mechanical fan.. i swapped in an electrical fan from Chrysler 300C V8... it has a bosch dual speed motor and blows really strong air"
While I agree with having a strong aux fan to help the AC out... I am against making all the engine cooling dependant upon electricity working in my car. The lack of ignition system and ability to drive home with fuses blown, alternator and regulator messed up and battery blown to bits is important to me...

Since water does a much better job of absorbing heat out in the air this is a nice solution... and you don't have to carry the water around except in the Summer...

My definition of ' Reserve Cooling' involves the time when stopped in traffic with no airflow due to moving forward before your set temp can't be maintained. For these purposes I do think that greater capacity at the point in the sysem where the R/D is really makes all the difference.... The compressor will only work longer when this is depleted (when you get moving )to get it back to working pressure... it will not work harder...then until needed the compressor will not know that there is greater capacity extant in the car. I have done a lot of reading and thinking about this since I originally posted this thread.... but have put off working on my AC unit because I refuse to do less than a perfect job flusing it. This means making the right fittings and recycling flusher/filter and doing pictures and narrative on it.

Hello leathermang
Your decision seems to be the best possible for a fair cost level.
I would suggest you check the fan fluid coupling function, and consider aftermarket engine fan options, any race shop will be glad to help you with information.

The bottle neck in terms of the physics is heat rejection of refrigerant through condenser.

#1. Heat rejection coefficient of condenser and refrigerant.
#2. Airflow
#3. Compressor RPM.
#4. System charge.

If your radiator is dirty outside, has leaf refuse between condenser/radiator, has scale built up inside, has damaged vanes = overloading the condenser
with heat.
A bad water pump, thermostat or loose belt will contribute to overloading the condenser with heat.
In Houston, Texas, it was common to change the OEM engine fan to a high performance high volume cooling fan = increase cooling 35%.
Swapping from the single row OEM condenser to a 2, 3 or 4 row unit is an aftermarket trick that does work.
A lower temperature fan switch can be installed, for arctic lovers.

How cold do you want it?
I can build and install a system that will hold -22F at ambient 134F in the hottest desert.
The question is do you want to pay for it?
Cooling is like speed, the more you want = the more it costs.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

"fan fluid coupling function,

I have no fluid fan coupling....

In other threads more directly talking about the aftermarket fan I have mentioned my desire to get a Spal Italian high capacity fan... I get all my AC stuff from Carlisle Auto Air in San Antonio and I think they carry them...

http://www.spal-usa.com/html/spalhome.htm

Spal fans are popular with the street rod/custom crowd; they make something to fit most anything.

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks, I did get the First Letter correct... those are the ones I was (trying) to think of....

So, Greg, this thread never reached a conclusion???

Did you get the parallel flow condenser installed and did it work out for you??

Inquiring minds want to know.

Other things happened to keep me busy... weather, farm machines, etc...Then season... did not see any rush during the winter....

Ahhh................would that be the winter of '03-'04 or the winter of '04-'05?