I've seen some discussion about the "door heat" ducts. Are they supposed to blow through the door panels? Around the front edge?
MB obviously put some thought into it as evidenced by the little rubber bellows and heavy ducts under the dash. I've noticed that the carpeted panels act as radiant heat for the footwells so is that it? Kind of radiant heat from the doors?
I think the door cavity is designed to be heated/cooled and insulate the interior passengers from the outside. Insulation is much more comfortable than simply blasting hot/cold air into the cabin.
I also don't see how the carpeted areas would provide radiant heat to anywhere. Perhaps you are missing the insulation behind the dash and footwells.
i think from memory, one needs to ensure they still have the clear plastic films in place over the insides of the doors otherwise that air is just going to blow inside the door and out the car 8)
I thought the plastic was to keep any water out that drips down the glass.
I was referring to the carpet that covers the plastic ductwork under the dash:
(http://i711.photobucket.com/albums/ww112/jhoff/IMG_2201.jpg)
There are no vents blowing air at your feet. The air just goes straight through to the doors but it warms the ducts/carpet up quite a bit as it travels through.
I will need to double check but I think there is a small hole in that duct work that opens to the foot well. The hole is small enough that I initially thought it was just to allow dirt to fall out of the duct but it could allow for enough venting to that area.
I think any heating of the panel under the dash is more a result of heat from the engine. If heat was meant to come through that area as you suggest, they would not have added carpet which would insulate the heat transfer more than the original non-carpeted plastic panels.
Quote from: Mforcer on 23 October 2011, 08:12 AM
I thought the plastic was to keep any water out that drips down the glass.
yes it does, but from memory if its not present the air will just go in the door and out the car ;)
I have another car that has the footwell duct part disassembled. I'll check it out as well. Thank goodness I'm not getting any engine heat bleeding through there! I drove it for quite a while in the warm weather with no ducts and didn't notice anything getting warm. It's just with the heat on.
I'm running without the carpet panel on the drivers side and that's when I noticed how warm the duct gets. I reached over to the passenger side and felt the carpet and it's warm as well.
Quote from: Major Tom 6.9 on 24 October 2011, 12:57 AM
...b the air will just go in the door and out the car ;)
I am suggesting that the air is meant to cool/heat the door cavity and not an issue if it does escape out the car.
I could be completely wrong but I would think blowing cooled/heated air onto the door panel as opposed to into the cavity will not achieve much.
well the plastic covers are supposed to be on the doors so i doubt the air is meant to go inside the door body, i think its supposed to go inside the door panel warming the whole thing and or allowing some to leak out around the arm rest ?
I recall reading somewhere that the door trims were heated so warm air passed over the side windows keeping them free from condensation. I always tried to feel for warm air rising up the window glass, and looked for a gap between the door trim and glass but never "felt" any air.
Heating from the underside of the parcel shelf is probably not in the design, air at that temp (I'm guessing 40-60degreesC) would conduct very poorly from the duct, across an air gap, onto the trim, and through the carpet. Eventually it would warm up, but as a deliberate source of heat, unlikely in the design. The forced air vents (convective as opposed to radiative) are the primary means of heat transmission there.
Thinking about this more, if the actual panel is intended to be heated/cooled, there is the question of how well it will transfer that heating/cooling and I would think that venting onto the panel itself will not dissipate in any meaningful way.
I am standing by the idea that the vent is into the door cavity itself and relatively little is lost to the outside of the car.
Do people have photos of original door panels? I suspect mine have been changed at some point.
Quote from: Mforcer on 24 October 2011, 04:59 AM
I am standing by the idea that the vent is into the door cavity itself and relatively little is lost to the outside of the car.
with all due respect, BS! ;D
I always thought that the foam sheet behind the trim was of an 'open cell' type which means that the vent air passes through it and through the corduroy cloth of the door trim.
After 37 years the original foam sheet has fallen into small pieces and all pieces gather where the corduroy/cloth meets the plastic bottom panel of the door trim (just above the pocket where you put maps and stuff).
I think it was MB's intention to create a smooth and comfortable flow of air through the door panel cloth, which was probably an innovation in those days (begin '70). I think it also helped to create the individual temp setting possibility (one for driver and one for passenger) which also was something new those days, I think.
I'm not writing facts here, I'm just contemplating.
But I've seen some discussions saying that this solution has saved many doors from rusting away :) It's a shame they didn't implement this in the back doors as well. I'm not sure but I think the foam in the back door trim is of a 'closed cell' type and holds much better after 37 years.
Originally however I don't think MB's intention was to blow air into the door cavity and out of the car, but to keep the warm or cold air inside the cabin to serve the driver/passengers.
As Arman has said, the air is prevented from entering the door cavity, as the ducting terminates at the outside of the door card. In the case of MB-Tex trims, the material is perforated.
Clearly, that is why the foam on the front trims differs from the rear.
Tim
Silly me thought that all w116's had corduroy cloth in the door trim. But obviously this is not the case. What type of material do the leather interiors have, where I have my corduroy cloth? Is that perforated leather just like MB tex has perforated material? And how does the back door trim look in case of MB tex or leather, non-perforated?
nice subject, cant believe only one of you is right and MT is so wrong!
that airduct brings the heated air into the door and rises up onto the front of the window so it defrosts. next time someone is driving in cold weather, crank your heaters and put the up defrost vents on and you will see this area defrosts on the window so you can view the outside rear view mirrors.
nathan
Quote from: arman on 24 October 2011, 08:58 AM
Silly me thought that all w116's had corduroy cloth in the door trim. But obviously this is not the case. What type of material do the leather interiors have, where I have my corduroy cloth? Is that perforated leather just like MB tex has perforated material? And how does the back door trim look in case of MB tex or leather, non-perforated?
My car had leather seats, but the perforated material on the door looked like vinyl or leatherette, it was perforated.
I had the door card off the passenger door once, and I had a quick look to see where air exited, but couldn't see anything obvious. It must be through those perforations, or else through gaps near the window seal, on the inside of the glass. I agree that air was prevented from going into the door cavity, there was no vent in the polyboard of the door card, and there was the plastic sheet also behind it.
Heating the door cavity would be a waste of heat. Better to heat the interior or directly onto the persons feet or body.
I can visualise the system working through the heat rising from the door card and/or being directed up to where the anodised trim sits against the glass.
It obviously works though.
Tim
It does indeed help keep the side windows defrosted, which is great if you have condensation from interior leaks. Also, I imagine it warms the mechanical parts of the window regulators so that they don't freeze up and not function.
the foam maybe open cell, but the wood its stuck to isnt 8)
Are we forgetting about that ?
I had planned to retract my statement and agree with Major Tom but nathan suggests otherwise. Is nathan ever wrong?
According to the owner's manual: A continuous draught-free flow of air is supplied through indirect door ventilation even when all the levers are in the position "closed".
I still don't understand what the engineers were trying to achieve by running the vent into a piece of wood covered in foam and perforated vinyl. The air flow would be severely restricted and unless there is air flow there is no cooling/heating.
I would also expect any perceived demisting of the side windows would be a result of airflow out the dash vents just under the windows.
Its good that their design is still the topic of much discussion and still not fully understood after 40 years 8)
Quote from: Major Tom 6.9 on 24 October 2011, 05:43 PM
the foam maybe open cell, but the wood its stuck to isnt 8)
Are we forgetting about that ?
Exactly, the fibreboard acts as a barrier... I'll show you a front door trim next weekend if I remember.
Tim
Yes I agree that the fibre board is the barrier and channels the ventilation air through the very open cell sheet and out through the perforated vinyl (leather interior) or (corduroy-)cloth material (velour or MB tex interior). I can understand why they call it 'draft free' this way.
But I don't see how this air can get to the inside of the window without first leaving the cloth/vinyl on the inside of the door? I would think that aiming the side ventilation directly to the side window would be a lot faster defrosting or demisting.
See here what some articles in the w116.org's library say about the front door vent ducts:
http://www.w116.org/library/autocar7307 (http://www.w116.org/library/autocar7307) (See text block besides 1st aid kit):
"All the running controls, like the indicators, wipers, washers, headlamp flashers and lamps are worked by a right-hand stalk and an adjacent rotary knob. On the left in the central console are the heater controls, above the position for the radio. Four vertical slides regulate temperature, independently for each side of the car, and distribution with a multi- speed fan switch between each pair. Pushing all slides up automatically gives maximum demisting. Independent of the heater is a com- prehensive fresh-air system with four face level outlets, all adjustable for volume and angle. Special ducts pipe hot air to the inner skin of the door trim pads where it forms a thermal envelope and incidentally keeps the door cavities free from moisture."
http://www.w116.org/library/autocar7405 (http://www.w116.org/library/autocar7405) (See text block besides the interior photo under 'Equipment'):
"No air conditioning equipment was fitted to the test car. The heater, however, behaved very well. Ample heat is available, and the distribution is good. Particularly appreciated is the ducting of hot air into the front door cavities - a feature which effectively demists and de-ices the side windows. So far as could be ascertained, there is no provision for ducting hot air into the rear footwells. The blower has four speeds, all but the highest of which (labelled "Defrost") are unobtrusive. Sensibly, the blower is arranged to boost the flow of cold air through the face-level vents."
Here is a link to what I think could be a suitable sheet of foam, if you ever want to renew the disintegrated original foam sheet: http://www.fipitaly.it/index.php?area=32&CTLGFIPIDC=97&CTLGFIPIDP=470.
It may sound thick however with 10mm but I think it is quite soft and will be compressed a little between cloth/vinyl and fibre board. It has to be really open to let the air through and out of perforated vinyl.
If you want to find an example of the foam type used in the front door trim, there might be left some similar sheet of it in the ventilation openings behind the shiny trim on the outside behind the back door. It should be there originally but it probably has also fallen into pieces and blown away after all these years.
Interesting discussion - let's revive it!
I noticed the door air supply is from the foot level ducting, so all up in def mode will not put air into the doors.
I noticed when i had one door apart there is a small but precise gap at the base of the glass all along the top of the door trim.
Also I agree there seems to be some porous material in part of the door trim.
My feeling is the primary reason was to keep side windows clear of moisture - but this would also increase warmth for driver or passenger.
What is this about different controls for left & right side? my 280SE doesn't have this; was this on higher spec cars?