AC Evaporator Box in 1982 300 TDT - Removal

The AC in my 1982 300 TDT has a fairly fast leak. If I get it filled it will leak out in a few days, which is too big a leak to seal with refrigerant additives. I have had about 3 charges leak out and they
all had dye in them. I have a small UV light and the yellow goggles, and also I took it to a place with a "sniffer." We can't find any leaks, but to check the evaporator you have to do major surgery on the interior of the car.
After removing the front seats, console and dashboard (or as Mercedes calls it, the instrument panel) I have exposed the following - have a look at the picture at:
http://inyopro.com/cars/wide_view.jpg
http://inyopro.com/cars/vertical_view.jpg
I have the shop manual for my car and the CD with all the manuals. I have the Automatic Climate Control type 3. The manual only shows the manual version of the Climate Control system, so I guess I have to wing it.
Has anyone ever replaced an evaporator in this type of system? Take a look at the pictures and you will see why I consider this a daunting task.
Thanks for any help. I called my AC guy and the labor charge is $1500 for them to do the job, so I have to figure this out somehow.
Paul
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Before you attack the evaporator look at the top of the receiver-dryer. It may have a brass hex plug into which is soldered a 1 or 2 mm wire blow-out plug. The solder breaks down and the plug loosens or blows out and the refrigerant is lost. It happened to my '80 and recently here to someone else who also couldn't find the leak.
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Unfortunately, 123 body evaporators leak a lot.
It is not that bad a job. I have done a hundred of them.
You did not have to remove the seats....
Disconnect the heater hoses at the firewall outside. Disconnect the AC hoses inside at the bottom of the expansion valve. Disconnect the main vacuum line going to the switchover valves. Unplug the wires going to the blower motor and evap sensor. Disconnect the 2 evap drain hoses going thru the tunnel floor. Remove the 2 straps. Lift out heater case assembly. Place on work bench. Remove lower section. Slide clips hold it together. Evaporator is in bottom of case.
"-->> T.G. Lambach <<--" <"T.G. Lambach at NoHamorSpamcomcast.net"> wrote in message

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If the evaporator leaks, then you should be able to see the dye on the windshield...assuming you did select bi-level AC mode.
Most common leak is at the expansion valve so take a look in there between your firewalls.
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You are thinking of the 126 body when you say 'between your firewalls'.
HE HAS A 123 BODY. A 300TDT is a 123 body turbodiesel station wagon!!!!
Do you read at all before you type???
A 123 expansion valve is under the glove box left side, INSIDE the car.

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Nah... I was thinking of W124 as in my car... 95 E300D. When I got mine... whoa... massive blowout there.
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Karl I think your response is combative and unnecessary. When someone responds to a request for help I appreciate their efforts. There is nothing to be gained by making a comment like "Do you read at all before you type?" Obviously if someone had not read the post they would not be responding whatsoever.
Please refrain from such comments in the future, especially, but not limited to, threads that I initiate.
Thank you.
I have already removed my expansion valve. Not doing so when I replaced the compressor and the cleaner (I have a new cleaner, so I don't think the solder on the plug is the problem) is probably what caused my evaporator to blow. The valve was old and crudded up and did not equalize the pressure properly. My AC place advised against doing the expansion valve, I realized later, because of the labor involved.
But then I did the research I should have done first and learned the function of the equalizer valve and then understood how essential it is to replace that valve when you do a new compressor because if you don't you will likely blow out your evaporator.
It really isn't much, however to just do that job, because you can get to it by just removing the glove box on my car. But it is much easier with the seats, console and instrument panel removed. I am not a small guy and I don't fit in there unless I remove all that stuff.
Paul Fretheim

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How about I don't reply at all and take my 28 years of MB dealership experience and know-how somewhere else?
No info is 100% better than wrong info.

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Karl wrote:

Bad idea ;)

True.
Ximinez
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Thank you very much Karl for the checklist. I have just been out looking at the job after sleeping on the whole thing after removing all the interior parts yesterday and was starting to get an idea of what to do. It helps a lot to know that detaching the hoses will indeed free up the heater box inside the plastic air chamber surrounding it and the evaporator.

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I had a hell of a time finding any dye despite the fact that three charges worth had leaked out. Finally I can see some flecks of dye on the drain hose coming out of the evaporator box, so now I know I am not wasting my time tearing the car apart.
I don't mind taking the seats out. It's only about 5 bolts per seat. My engine is being remanufactured right now and I am glad to tear everything out and clean all the carpets and stuff. I got rid of all those idiot warning beeper connections a long tme ago.
I learned one thing the hard way just now though. Don't try and machine wash those thick custom sheepskin seat covers, even on the delicate cycle in Woolite. I destroyed a $250 seat cover. Then I carefully hand washed the other one and the arm rest cover and the head rest covers and they came out fine. I figured out that the hides get soft when they are soaked and when the washer spins it rips all the wool fibers from the hide. But when you hand wash, if you are very gentle with the sheepskin until it dries, they regain all their strength and are just fine.

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