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Old 06-20-2010, 04:34 PM
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Is vacuuming under W126 fusebox enough?

We charged the A/C on my mothers 88 W126 today and it had been running with the A/C (fan) on high for about 20 minutes. We turned it off and I kept getting whiffs of what smelled like "hot wood" and I traced it down to the fuse box area... not in it, but around it. It dont smell electrical, it smells like someone has used a wood burning kit. I looked and natually there are alot of leaves in there and I am assuming I was smelling those heat up? I was told once that the A/C / (fan) relays were under there and get very hot. We have not used the fan in a long time (since winter when the heat was used).

I am wondering if vacuuming it alone is sufficient or should the fuse box be removed somehow to get them all? Seems like a lousy design on MBs part.

Thanks

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Old 06-20-2010, 06:29 PM
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OMG, you would not BELIEVE all of the crap (leaves, twigs, paper, etc)! that came out from under the fuse box area. There is one thing that looks like a relay at the bottom that was covered in like 2 inches of leaves/twigs. Its a wonder this car has not burned up years ago! I never dreamed there was that much debris in there.

I had been meaning to vacuum it, but kept putting it off. Apparently part of the A/C heater blower components are under there and heat up... I started the car again and felt of that relay and it was hot, so its a wonder it had not ignited when all of those leaves were under there. Just when I thought I was finished, I would find more and hear it sucking more leaves/twigs. I could not get so much directly under the fuse box itself, as that seems impossible, but I dont think there is anything actually under the fusebox itself in the way of relays? That one relay I mentioned... I was able to get my finger to drag out more crap, but the vac would not get anymore out... I am sure there is still maybe some wedged under there, but I dont see how one could get it, but I think I got as much as possible and it should be OK now. What a crappy design on an otherwise well designed MB.

This is my mothers car, she is 55 and she uses this car to take my baby nephew to therapy 3 times a weel (which is 60 miles per day round trip) and I dont want a fire to break out on her... she would have no idea what to do. Maybe the smell had been there all along, even without the A/C fan on, but we had never had the hood up with it on to smell it.

Hopefully its OK now.
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Old 06-20-2010, 08:29 PM
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If your still concerned you might want to mount a battery disconnect someplace she can reach without getting under the hood.

Extinguisher might be nice too.
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Old 06-20-2010, 09:30 PM
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Thanks. Yeah, I carry an extinguisher and first aid kit in all of my cars and moms too, just to be safe.

Well I went back out and vacuumed more and there is "nary" a leaf or anything under there now, so there is really nothing to catch fire now in the way of foliage. Should be fine now. I drove the car 59 miles this evening with no fanfare (after I had vacuumed in there), but I didnt use the A/C. I am going to drive it to work all week, using the A/C (as its supposed to be in the low-mid 90s all week.

I just cannot believe all of the crap tha was down in there... dry crisp leaves (mostly from a Live Oak tree)and Loblolly pine tree needles and like I said, even some kind of paper with a coat and hat size and a small piece of newspaper! All of that was on top of a relay that I think works the A/C or fan because that only got hot when I had the A/C on. If I hadnt of noticed that smell (apparently it had just really started heating that mess up), she could have very well went on that long drive on Wednesday with the A/C and probably about 15 miles down the road (if that), I am sure it would have not been pleasant.

Word to those with a W126, if you have not cleaned out very well in around your fuse box area and well down below, you may want to get the old vacuum cleaner out with the narrow attachment and vacuum, vacuum and vacuum.
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Old 06-20-2010, 09:49 PM
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1983-300SD

I had nearly the same thing happen to my SD. I charged up the AC while jumpering the AC Compressor and then I smelled smoke and had a small fire just below the passenger side of the Brake Booster. Their is a small part located there about 3 inches by 2 inches that I can see into where there are exposed coils that were red hot and started the leaves on fire. It is a plugin unit with pins. I don't know what it does or what it is for... Any help would be appreciated. The same kind of unit is in the 123 Euro model and it is located on the inner fender well on the passenger side. I have also seen this type of unit behind the glove box... Jim
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Old 06-20-2010, 10:02 PM
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Hmm... yeah it seems like those relay(s) are down on that side. I just took some pics, I will post and try to circle what I think is the A/C relay.

Yeah, if I hadnt of smelled it, we may have had a fire too. It was not even smoking yet, but I was just getting whiffs of hot wood (like someone had a wood burning gun). It dawned on me then that these cars have that leaf trap down in that area and I think it gets hotter when you use the heater/AC. Must be a fan relay or something or a relay for the A/C compressor.

Its a known design flaw on the W126.
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Old 06-20-2010, 10:22 PM
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Quote:
Originally Posted by jim16671836 View Post
I had nearly the same thing happen to my SD. I charged up the AC while jumpering the AC Compressor and then I smelled smoke and had a small fire just below the passenger side of the Brake Booster. Their is a small part located there about 3 inches by 2 inches that I can see into where there are exposed coils that were red hot and started the leaves on fire. It is a plugin unit with pins. I don't know what it does or what it is for... Any help would be appreciated. The same kind of unit is in the 123 Euro model and it is located on the inner fender well on the passenger side. I have also seen this type of unit behind the glove box... Jim
Yep, I pull my battery once a year and use a blower to blow out all debris on both sides -HIGHLY ADVISIBLE!
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Old 06-20-2010, 10:25 PM
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Wow, I didnt know about the battery side... other than the battery connection, are their relays on that side too?
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Old 06-20-2010, 10:36 PM
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Here is a pic I took this evening. This that I have circled in red was covered in about 3 inches of dry leaves/sticks, etc. After I got the leaves out, I started the car, turned on the A/C and this gets hot! That was likely what I was smelling when the A/C was on. It has a wire to it nad its like a ceramic box....



other pics after cleaned... all of this was covered in the bottom with leaves/sticks/paper....



Here is a pic I took a couple of months ago before I cleaned it....

this was a fire waiting to happen!




here is the battery side I took a few months ago (I have since unhooked that wire that went to the CD changer) - still need to clean that side I guess.

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Old 06-21-2010, 12:13 AM
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This applies to ANY MB Chassis ! Not just the W126.

Even if you "Garage" your Automobile,a quick visual twice a year only takes minutes.

Leaves,Sticks and other Organic trash:
1.Block the "Natural" under hood Airflow.
2.Create the Perfect environment for RUST (Corrosion).
3.Provide a fuel source/accelerant for Car-B-Que(s).
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Old 06-21-2010, 01:42 PM
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Ja, das ist eine BIG CERAMIC RESISTOR. Yeah, it gets quite hot.

It amazes me how much crap gets under there. I would definitely call it a design flaw. I vacuum out under there three or four times a year at least, and I remove my battery trays at least once a year to vacuum under there. The engine computer gets pulled too, as stuff collects under it too.

The real ***** of it is that a large shop vac hose will not fit in there, and the small hose gets plugged up too easily. I usually wind up with the large hose shoved as far in there as it will go, and a stick or something to push the leaves towards the hose. What a pain.

I would pay good money for some sort of retrofit to the hood or firewall that blocked that stuff out better.
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Old 06-21-2010, 03:55 PM
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With an air compressor it is very easy (but the leaves go everywhere).

Rob
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Old 06-23-2010, 02:08 AM
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Yeah, that only seems to get hot when the A/C (or at least the fan) is on, so it must be an A/C thing.

I dont know when it was last cleaned out... maybe never. lol.

Yeah, it was a pain to get all of that out... just when I thought I had it all, I could it hear it sucking out more. I had used the regular home vacuum and had put on that narrow ended attachment and it kept getting clogged, but the leaves were so dry and crisp, I just had to touch them and they crumbled. Like I said, there were about 3 inches of that crap over that resistor... had I not smelled it and cleaned it out, I am sure my mother would have probably had a fire using the A/C on one of her trips out. I have been driving the car for the past 2 days using the A/C and its been OK, so I guess I got it all... or enough anyway. Sure going to have to keep a check on it from here on in. Like Rob mentioned above, I was going to use the blower from the air compressor, but I knew it would go everywhere. I may go back with that though and see if I can get whatever may be left under that resistor. My mom has to use the car for the next 2 days, but I kinda told her not to use the A/C until I had a chance to try it out more... hard to tell her that though considering its supposed to be in the mid to upper 90s here for the next two days. The A/C is still not up to full capacity anyway. It gets cold, but not nearly as cold as it should be... he put two cans of R134a in, but it may need another. Also, boy dont the A/C really drain down the power of a M103 powered LWB W126?

Quote:
Originally Posted by tinypanzer View Post
Ja, das ist eine BIG CERAMIC RESISTOR. Yeah, it gets quite hot.

It amazes me how much crap gets under there. I would definitely call it a design flaw. I vacuum out under there three or four times a year at least, and I remove my battery trays at least once a year to vacuum under there. The engine computer gets pulled too, as stuff collects under it too.

The real ***** of it is that a large shop vac hose will not fit in there, and the small hose gets plugged up too easily. I usually wind up with the large hose shoved as far in there as it will go, and a stick or something to push the leaves towards the hose. What a pain.

I would pay good money for some sort of retrofit to the hood or firewall that blocked that stuff out better.
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  #14  
Old 06-23-2010, 03:36 AM
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This is a known issue for the W126 chassis. There has been a DIY link here on the subject for quite a while.

http://www.peachparts.com/Wikka/W126EngineTrough
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Old 06-23-2010, 06:39 PM
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Yeah, I remember this now. Yes, that resistor gets very hot. Apparently like I mentioned, it only gets hot when either the A/C or blower is on... I havent checked it yet to see when it gets hot, but when I had the A/C on it got hot. Good feeling to know its cleaned out now...

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