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Old 05-04-2005, 04:23 AM
Greg in Oz Greg in Oz is offline
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Join Date: Jan 2003
Location: Sydney, Australia
Posts: 627
Alex,
It's a tough decision. Many recommend staying with R12 and some even go so far as to say they wished they never changed to R134a and would consider changing back. Having said that, our 300TE had an R134a conversion prior to us purchasing it in 1998 and I have always been perfectly satisfied with its cooling performance. Of course, I never knew how it performed with R12. In the wagon it even has a larger volume to cool than a W124 sedan or coupe although it has a slightly larger compressor than that in my W201 (not sure which compressor the 124 sedans and coupes got). The 134a has also only needed one top-up in the time we have owned it. Logic suggests that the appropriate time for an R134a conversion is when the system is open and parts are being replaced. It is just a case of do I do it now when it is being opened for only a receiver-dryer and O-rings or do I wait until when something more major such as the compressor, evaporator or TX-valve requires replacement? Is the amount of oil required also not that critical? I am surprised there is not more "science" involved to the quantities required following a leak.

Larry,
Interesting comments re the price of R12 versus R134a. I am not sure how they compare here other than to say that it seems to be difficult to find someone with R12 and that they charge a lot for it. Our summers in Sydney are fairly demanding on the air-con with humid days reaching up to 35 degrees C (90 F) and dry days sometimes exceeding 40 C (105 F). Based on this and comments by you and others regarding both the loss of efficiency and the greater chance of leaks and other problems with 134a, I am tempted to stay with R12 for as long as possible. It is disappointing that dye was not added with the last lot of R12 but he seemed to only want to add gas and sniff for leaks. The leak at the receiver-dryer is very obvious with the whole unit covered in a film of oil. Whilst the leak at the compressor does not seem as bad, it is enough for some of the oil to have dripped onto the lower engine bay cover and leave a large patch there. Looking closely at the compressor reveals the oil seems to be leaking only from the manifold with the area around the shaft and clutch perfectly clean and dry. This suggests the O-rings at the manifold need attention in addition to a new receiver-dryer. How about I replace just these items (without disturbing anything else) and go with another charge of R12 and oil (hopefully with dye this time) and see how I go? I can only hope that the rest of the system is OK. I don't believe the evaporators in the W201 to have such a bad reputation as those in the W140 or even the W124. Despite the similarities between the 124 and 201, at least in the 201 the evaporator is much easier to access than in the 124. With its placement forward of the firewall it is accessible from below the wiper mechanism (rather than pulling all the dash inside the car). This location also means that condensate flows into the area between the two firewalls and then via the rain-water drains rather than separate drains as in the 124. This would also allow dye to be detected in this area prior to it reaching the ground underneath the car.

Thankyou both for your valued feedback and opinions,

Greg
__________________
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.
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