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  #16  
Old 08-13-2013, 11:57 AM
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Originally Posted by vstech View Post
....................................................................................
the "dryer" in an automotive system is nothing more than a can with a tube in it, and a desiccant bag inside to absorb moisture. it has zero filtering capabilities. if the system has black residue in it, a LIQUID line filter needs to be installed in the line between the dryer and the condenser. this will polish the oil and remove all traces of black death.
I remember cutting open a dryer (either from a W123 or a VW), in addition to the desiccant basket, there was a membrane filter in the form of a sheet spanning the inside diameter of the dryer. Was that unique to the one I cut open? It's not pleated so won't hold much but it is a filter.

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  #17  
Old 08-13-2013, 12:08 PM
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Originally Posted by Air&Road View Post
You should replace the rubber and THEN flush, flush and flush.

You don't need to buy all new hoses, it would cost a fortune. Take them off and take them to your hydraulic hose shop or local automotive a/c shop. Either of them can replace the rubber portions of the hoses.

While the hoses are at the shop, thoroughly flush and THOROUGHLY blow out the flushing agent from the components. About the only components to flush will be the evaporator, condensor and expansion valve.

After everything is back together, put the filter drier in place as the very last step, but don't do it until you have the vac pump in place and ready to go. As soon as you tighten the connections on the filter drier, turn on the vac pump.

Good luck with it.
I am quite familiar with A/C hoses (I make my own and sell them with the Sanden kits). The only 2 remaining hoses are the ones that go into the cabin (low side from the hard pipe, high side from the drier). I agree that it is a good idea to replace all the hoses. However, the small high pressure hose (blue, sometimes black) is made of some different kind of material, and probably is not the cause of the black stuff. I imagine that the large hose is more the culprit. I will suggest replacing it before charging, and installing a liquid line filter as well.....Rich
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  #18  
Old 08-13-2013, 12:16 PM
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Originally Posted by funola View Post
I remember cutting open a dryer (either from a W123 or a VW), in addition to the desiccant basket, there was a membrane filter in the form of a sheet spanning the inside diameter of the dryer. Was that unique to the one I cut open? It's not pleated so won't hold much but it is a filter.
I have a pile of old 123 driers, I may dissect one and see what is inside.
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  #19  
Old 08-14-2013, 10:01 PM
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Originally Posted by vstech View Post
do you have any idea what the "BLACK DEATH" is?

in an electrical compressor, black death is from the winding insulation burning inside the compressor... there is no winding inside an automotive compressor...
the aluminum and copper if corroded from acid should form either a green or a white sludge... what's left to make black slime? the rubber hoses... so... they should be replaced. and modern hose has a "barrier" that keeps the pag and 134 from attacking the hose and leaking out.

My thought are that the rubber hoses should be replaced, and the metal parts flushed and filtered.
the "dryer" in an automotive system is nothing more than a can with a tube in it, and a desiccant bag inside to absorb moisture. it has zero filtering capabilities. if the system has black residue in it, a LIQUID line filter needs to be installed in the line between the dryer and the condenser. this will polish the oil and remove all traces of black death.
Don't believe a liquid line filter can 'polish' the contents of the system any better/finer than the receiver/dryer.
It is much more than a desiccant bag. It involves a fine mesh screen then a very fine thick woven material sandwiched on both sides of the desiccant material. I can't visualize any better filtering in a smaller can.

And, it WILL load up quick after any compressor failure.

Would you like to see pictures?
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  #20  
Old 08-14-2013, 10:20 PM
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Originally Posted by Whiskeydan View Post
Don't believe a liquid line filter can 'polish' the contents of the system any better/finer than the receiver/dryer.
It is much more than a desiccant bag. It involves a fine mesh screen then a very fine thick woven material sandwiched on both sides of the desiccant material. I can't visualize any better filtering in a smaller can.

And, it WILL load up quick after any compressor failure.

Would you like to see pictures?
I am thinking I will dissect the drier that came out of this car just for fun. I am also having a hard time finding the right liquid line filter anyway. The only one I can find has barbed ends, and I need either #6 Oring, or at least 3/8 flare. I also need a small one, as the area is tight where it goes (near the SLS reservoir). Yes photos are always helpful....Rich
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  #21  
Old 08-14-2013, 10:36 PM
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For the non believers...

Here's is a dryer that was run for one season after a replacement R4. The previous R4 was weak but still pumping. No "black death' here yet there's evidence of the first layer of filtration loading up.
Attached Thumbnails
"Black Death" found when when flushing. FULL COLOR PHOTOS-photo-27-.jpg  
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  #22  
Old 08-14-2013, 10:50 PM
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Beneath the screen, seen here with the tube protruding, is a woven layer approx 8-10mm thick, below that is a 30-40mm layer of tightly packed desiccant beads. Then another layer of woven filter followed by another fine screen. The top layer of woven material usually loads up with small metallic particles. Clean (polished) contents exit through the tube.

Change the dryer after a short run as good insurance. It's cheap and you can reuse the recovered freon.
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  #23  
Old 08-14-2013, 11:38 PM
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"do you have any idea what the "BLACK DEATH" is?

in an electrical compressor, black death is from the winding insulation burning inside the compressor..."

Whoever said this, are you sure? The only windings in a compressor is the clutch solenoid, which has no need to be inside the compressor (where the oil is).
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  #24  
Old 08-14-2013, 11:59 PM
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Quote:
Originally Posted by funola View Post
"do you have any idea what the "BLACK DEATH" is?

in an electrical compressor, black death is from the winding insulation burning inside the compressor..."

Whoever said this, are you sure? The only windings in a compressor is the clutch solenoid, which has no need to be inside the compressor (where the oil is).
which is why you should not snip lines from a quote...

Quote:
Originally Posted by vstech View Post
do you have any idea what the "BLACK DEATH" is?

in an electrical compressor, black death is from the winding insulation burning inside the compressor... there is no winding inside an automotive compressor...
the aluminum and copper if corroded from acid should form either a green or a white sludge... what's left to make black slime? the rubber hoses... so... they should be replaced. and modern hose has a "barrier" that keeps the pag and 134 from attacking the hose and leaking out.

My thought are that the rubber hoses should be replaced, and the metal parts flushed and filtered.
the "dryer" in an automotive system is nothing more than a can with a tube in it, and a desiccant bag inside to absorb moisture. it has zero filtering capabilities. if the system has black residue in it, a LIQUID line filter needs to be installed in the line between the dryer and the condenser. this will polish the oil and remove all traces of black death.
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  #25  
Old 08-15-2013, 12:55 AM
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Originally Posted by Whiskeydan View Post
Here's is a dryer that was run for one season after a replacement R4. The previous R4 was weak but still pumping. No "black death' here yet there's evidence of the first layer of filtration loading up.

I cut open a receiver dryer off our 123 several years ago to see what was inside. It only had some desiccant material in the bottom, but no other filtering material. Must be different grades of them?


Charlie
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  #26  
Old 08-15-2013, 01:05 AM
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Originally Posted by charmalu View Post
I cut open a receiver dryer off our 123 several years ago to see what was inside. It only had some desiccant material in the bottom, but no other filtering material. Must be different grades of them?


Charlie
Could be...
This was on a '79 300SD W116. The dryer was from China as most are nowadays.
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  #27  
Old 08-15-2013, 01:09 AM
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This is a very interesting thread as I'm thinking about getting my AC system in my 78 300D working again.

As for the black stuff, is there any known silver solder in any of the hard lines? If metallic silver is oxidized, it turns pure black (I'm a photographer, so I think about this reaction a lot even though the latent image is in a non-metallic silver halide in the case of a photo.) My theory about this black death is that there is a silver-based solder in one of the hard lines or a heat exchanger and it has oxidized and deposited itself throughout the system in the very fine (3-6 micron grains) powder that makes a photo a photo.

Just a theory though!

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  #28  
Old 08-15-2013, 08:38 AM
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Quote:
As for the black stuff, is there any known silver solder in any of the hard lines?
Shouldn't be. The lines are formed from solid tubing using dies. None of the ends are attached. I'd be more inclined to expect solder in heat exchangers if they are copper/brass construction. I haven't enough Mercedes experience to know if / when MB stopped using copper/brass.

Quote:
My theory about this black death is that there is a silver-based solder in one of the hard lines or a heat exchanger and it has oxidized and deposited itself throughout the system in the very fine (3-6 micron grains) powder that makes a photo a photo.
Interesting. Are you thinking the system should be changed to modern aluminum components to see if anything new develops?
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  #29  
Old 08-15-2013, 11:24 AM
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Originally Posted by vstech View Post
which is why you should not snip lines from a quote...
I did that because it was unclear to me who made that statement of electrical windings is the cause of black death. I went back and searched the thread and it appears that, since you did not quote anyone, that you made that statement and challenged it in the next sentence. Now I am confused why you did that.
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  #30  
Old 08-15-2013, 03:46 PM
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I did that because I do not know what causes "black death" in automotive refrigeration systems... there's no electrical winding to burn up in there, so what is making it black? could it be the black rubber from the lines breaking down from the acid in the oil? could it be the friction from a siezed piston burning the oil? I do not know... that's why I made my post.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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