Change from r12 to r134 by MB factory for 124 chassis
 

When the factory changed from r12 to r134 in the 124 chassis cars, they used different O rings, low and high pressure hose fittings, oil, and amounts of refrigerant.

Are there any other differences between the two systems?

Thanks.

They might have upgraded the type of condensor and the aux fan ?
They might have used a Txvalve set for R134a instead of the R12 one...

Hoses are different also, whatthey refer to as "barrier hose" on the 134a cars. I wouldn't doubt the evaperator, condensor, and expansion valve may vary between the two, although 134a is still considered almost a drop-in, the 134a in R12 cars are known for not cooling as well at city speeds.

Right, which is why I'm trying to figure out why factory equipped r134 systems cool better than R12 systems converted to r134.

The vent temps for my 91 TE (converted to r134 by PO with new compressor) are so much warmer than the vent temps for my 93 CE (r134) and the 95 E300 (r134).

Online parts stores sell the same condenser, compressor, evaporator, and expansion valve for 1991 (R12), 1993 (r134), and 1995 (r134). I already know all three years have the same aux fan.

Just now checked the EPC, which shows the same condenser, compressor, and evaporator for those R12 and r134 years. However, EPC shows expansion valve 140 830 06 84 for R12, but 140 830 04 84 for r134.

So, it seems to properly convert a factory R12 system to r134, one needs to use the newer style barrier pressure hoses, and be sure to have the r134 type expansion valve, along with green O rings and r134 size schrader valves.

And yes, of course, the bloody TE should never have been converted in the first place:(:(

R134 convert
 

Maybe I will try the 134 expansion valve. my 88 300e never was as cool as the R12,but I am in Vegas the summer is brutal unless your windows are limo-blacked out. ac is very important here in the summer you will start to see spots just before you blackout! Now that I have my r12 license I would like to convert back but am to busy with other projects to flush the system of the pag oil:D

Any reason not to use drop in replacements like Freeze12 or Autofrost? Worked great on a few cars I've used them in.

Ahem... !
 

The 134 Does not have the "Heat Transfer Rate" of the R12.
To successfully "Convert" an O.E. R12 W124 to 134:
1.Larger capacity CONDENSER A.K.A. "Parallel Flow".
2.Compressor DESIGNED and Constructed for the HIGHER Operating Pressures of 134.
3.134 TX valve
4.New 134 "O" rings (AND O-ring Lube)
5.New "Barrier" type Hoses. (The 134 [and it's lube] will bleed through the R12 hoses over time.)
6.Flush everything Except the New Compressor.
7.New Receiver/Dryer.

Without these as a Baseline:
All 134 W124 "Conversions" are Doomed to a shorted life span due to the Higher
pressures exerted on the OLD R12 components.

Then You're "Gambling with the Mafia" over the Evaporator surviving very long
with the excess 134 pressures,given their propensity for LEAKS with R12.
(Thank You Behr !)

Frigid
 

Y'all wanna be Frosty in a W124?
R12 with a Parallel Flow Condenser!

Yes I do. Please post manufacturer and model number. And how MB fittings are connected to it.

Thanks.

Call the guys at ACKITS
 

http://www.ackits.com/

Arizona Mobile Air

To consult on the correct size Parallel Flow Condenser.

'Remember y'all are going "Outside the Box" (This is not "Plug and Play")

The Location of the Hose Connects will not match the factory attachment points. So you'll have to have a new set of hoses custom fabricated.

Yes, I know, which is why I am asking what you did on your car, and that you share that experience with us.

Parallel Flow
 

1.Measure your old Condenser(Record the measurements!)
2.Select the New Parallel Flow Condenser that will FIT.
[Your Due Diligence in comparing the New Parallel Flow Condenser's Capacity
to the Old Condenser's Capacity will tell you if you're "Chasing the Dragon"]
3.Take Both OLD and New Condensers (AND the Hoses to be replaced)
to the Hydraulic Shop.So they can "SEE" the extra amount of Hose needed and
the Fittings to "Make Up" the New configuration.
(They'll use your old fittings and New "Barrier" type hose to make new ones.)

You'll have to McGuiver the fittings and Rubber Bumpers to secure the New
Condenser into the Old One's Slot.

The expansion valve hard up against the firewall looks like a bear to remove. Anyone have any experience with this? I'd like to replace it.

BTW just had my '88 300E refilled after a conversion a few years ago. Only getting 50F at the vents on an 80F day. No where near as cool as my other old cars that have been converted.

convert to R12
 

ds190,

http://www.peachparts.com/shopforum/diesel-discussion/279659-thinking-going-back-r12-134a.html?highlight=convert+R12

http://www.peachparts.com/shopforum/search.php?searchid=5754556

Replacing expansion valve
 

I've replaced the expansion valve, it was not fun, and I have small hands! See attached pdf.

BTW, I am very happy when I get 50 degree F vent temps in my converted-by-PO-to-134 TE:)

So, you have not installed a parallel flow condenser in your 124, is that right?

Thanks for the link to ackits.

Just had my fittings and o-rings replaced in my w124 300E '91 to retro from R12 to 134. I had a leaking high pressure hose and now it blows ice cold. No new drier or parallel flow condensor added. I'll post back if and when it starts going bad.

I have to refute the claim that R134A runs higher pressure. In fact there is a R134A specific high pressure switch that cuts the fans on about 50PSI lower than the R12 switch does. 250 v/s 300 You can tell them apart by color, the green switch is for R134A and the red one is R12. A proper conversion will require swapping in the lower rated switch.

Eh ?
 

ds190,

The ONLY thing left in the HVAC "Cooling" system that made the Original trip
from Sindelfingen VIA Hamburg on the Chassis in 1990 is the Compressor.
[It (The Compressor)does have New Seals,Inside AND Out.]

"It's ALL About Condenser Capacity"