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...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

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.

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Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

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

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

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

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

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.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

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"

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'84 300SD sold
124.128