Early A/C system to later retrofit plus r12 - PeachParts Mercedes-Benz Forum

ps2cho · #1 03-15-2013, 09:48 PM

So this will be my official progress thread as I attempt to make the best A/C system possible using only factory parts.

My 300TE is currently switched to r134a and it just doesn't cut it out here in Arizona.

Parts to upgrade:
Old 15cc to New 17cc Denso Compressor
Larger Condenser
Twin fan assembly
New Drier
R12 refrigerant

So basically, Mercedes used a larger condenser, larger compressor and better twin fan design to improve on the shortcomings of factory r134a system.
If I upgrade to that design, BUT use R12. How could it possibly get any better, right?

----

So went to the junkyard today and found a complete assembly with working fans (tested using portable battery).

The Fan and condenser should be easy....The only problem I think I will run into will be with the different placement of the hoses as shown below:

Early Model:
[IMG]https://www.***************/secure/PartImages/1248301770.jpg[/IMG]
Later Model:
[IMG]https://www.***************/secure/PartImages/1248301670NIS.jpg[/IMG]

Compressor Hose:
Early Model:

Later Model:

Does the 17cc compressor REQUIRE the later hose, or will the original one fit? Anybody know?

LandYaghtLover · #2 03-15-2013, 10:39 PM

Well the system could freeze up. Colder is not always better. But I am no expert. I use propane as a refrigerant in my cars that call for R12 after all!

ps2cho · #3 03-16-2013, 01:27 AM

In 120F, no way its gonna freeze up!

ps2cho · #4 03-19-2013, 04:04 PM

Just purely out of the curiosity and to keep within my budget, I have decided to do this in two stages:

Stage 1: Bigger condenser and dual fans sticking with R134a.
I want to see what immediate difference it makes with R134a with the small upgrade. Since the later condenser is still the same tube and fin design, I can simply flush it clean when moving onto stage 2

Stage 2: 17cc compressor and R12.

Will update soon with Stage 1 progression! Awaiting the condenser in the mail.

ps2cho · #5 03-19-2013, 07:42 PM

Took a closer look tonight at the hose assembly. Definitely needs to be changed to make this work....

After some hunting my stock suction hose /w fuel cooler: PN # 103-130-17-57 shown below: (for future researchers replaced by 103-130-38-57 followed by 103-130-32-57 all same unit same as photo below)

Superceded to 103-130-53-57 (THIS looks like its the one I need) shown below:

Note the longer line that bends around towards the top of the original condenser:

Versus the superceded part # that is shorter and simply bends at a 90deg angle to go to the new location of the outlet.

Interesting enough I just noticed something...

It seems that as of 1990 onwards, they ALL use the later model condenser. If you plug a 1990 300E and a 1994 E320, the condenser has the same part # and the same location of the outlets. I guess then that in fact contrary to common knowledge, models with R12 between 1990-r134a introduction had the best systems! They came with the later condenser (is it even any bigger now??), the dual fan set up and the sweet R12

The ONLY thing that changed with the r134a systems was the Nippodenso 17cc compressor. That's ALL! I am going to guess that they only replaced it because at IDLE R134a was struggling hard so to compensate, they gave it a boost.

Gilly · #6 03-19-2013, 07:58 PM

I wouldn't do it, but can see you've made your mind up.
Technically, the problem I wonder about are the fittings. The R12 fittings have the threads that the 134 adapters screw on to, but how do you get R12 fittings on to the 134 connectors?

I think the system will "cut it" once the updated and later 124 components are added (that were made for factory 134a cars). R12 conversions are known for being subpar, but that is not only because the 134 isn't as good as the R12 (we know it's not!), but also because the system was designed for R12, once you drop in 134, yeah it's a lose-lose situation. Once the system is upgraded to 134-spec components it will be a lot better. In my opinion.

Gilly · #7 03-19-2013, 08:01 PM

Quote:

Originally Posted by ps2cho

Just purely out of the curiosity and to keep within my budget, I have decided to do this in two stages:

Stage 1: Bigger condenser and dual fans sticking with R134a.
I want to see what immediate difference it makes with R134a with the small upgrade. Since the later condenser is still the same tube and fin design, I can simply flush it clean when moving onto stage 2

Stage 2: 17cc compressor and R12.

Will update soon with Stage 1 progression! Awaiting the condenser in the mail.

OK I see so you are going to see what happens with the condensor. I would give it a chance with the new compressor and 134 as well. I know you have more extreme conditions out there. I wonder what difference it makes that you guys are hot and dry and we in the midwest are hot and humid?

ps2cho · #8 03-19-2013, 08:06 PM

The hoses used in 1990-1991 connect to the later condenser, but still have the r12 fittings because in those model years, r12 was still used. You can see from the 2nd photo above. That is what I found out through this research. The so called "later" condenser in fact was used with R12...its not an R134a enhancement.

Ivanerrol · #9 03-19-2013, 08:39 PM

I have a series II '90 W124 ex Japan.

It came with R12 and I still use it. The car has the dual fan setup and larger Denso condenser. The rear pipes for the condenser fit in O.K.

The trade off is that changing the water pump is extremely difficult. There is very little room behind the pump and above the condenser.

My setup works well. The dual fans only come on when the engine temp reaches 110. or in traffic. The R12 gas in my system is at the correct level. We have over 110 degree Fahrenheit temperature days in summer also.

ps2cho · #10 03-19-2013, 09:14 PM

Does the hose go behind the water pump??
It doesn't go to the side of the power steering pump?

Happen to be able to snap a picture?

lorainfurniture · #11 03-19-2013, 09:37 PM

You can create a fitting to makeup the distance between the old style to. New, otherwise go back and get the hose.

If you are going to do it, do it all at once. Every time you open up your system you re- contaminate it. I wish you were closer because I have everything you could ever need to do it right the first time. Spring for the nitrogen tank, keep in mind you can start filling your tires up with it as well

The regulator and misc stuff can be had on fleabay.

So says the guy with really cold a/c.

Ivanerrol · #12 03-19-2013, 10:34 PM

Quote:

Originally Posted by ps2cho

Does the hose go behind the water pump??
It doesn't go to the side of the power steering pump?

Happen to be able to snap a picture?

Sorry - Nephew has my W124 at the moment - I'm fixing his W202.

You sort of see it here

ps2cho · #13 03-30-2013, 12:25 AM

Got the condenser in today...So pretty

Went with Behr over Nissens because I got the hookup on a brand new Behr for the same price as the Nissens so since MB used Behr as the OE, I went with Behr. Says made in Thailand..
I am going to TRY and see if I can simply bend my current A/C to fit instead of paying for a new hose simply for location. It may work since I can bend the metal. Worst case I have to get the new hose from the junkyard. No biggie. Will report back if it works.

Next up is to evacuate system, remove radiator, attach dual fan assembly, install everything, add oil and recharge.

Now -- I have had nothing but large pressure before with r134a. Should I instead charge by low side and by measuring the evaporator temperature? Is that a better way than simply doing 80%?
The system wouldn't even ACCEPT 80% of the weight before.