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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #1 ·
Hello all,

I have had the heated seats option retrofitted into my 107. All the parts are original and new including the wiring, heater pads, relays and buttons. The car has MB tex cream on it.

It takes at least 10 to 15 minutes for the seats to warm up and only slightly. I'm not particularly impressed by the level of heating the heater pads produce. There's 3.5 amp going to the pads on low setting and 5amp on the high setting. My intention was to use the heated seats on chilly days with the soft top down.

Any users on here who could please elaborate on their experience with the heated seats option? Am I expecting too much or should the seats really be heating up? Should it really be taking 10-15mins to start feeling the seat only slightly warm up?

Appreciate any input on this matter
 

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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #5 ·
Are the parts new?
All the parts are new and original. The local Mercedes branch sourced them based on the new EPC program. The heater pads have different part numbers depending on whether the car is fitted with MB tex/velour/cloth etc. Mine has cream MB tex. Below a photo of when the pads were installed at the upholster. I took the car out for a drive last night, it took 10-15mins to feel the seat getting warm, barely! I used a temperature gun, the difference was only 5 degrees celsius between the passenger seat and driver seat.


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1972 350sl 240k miles silver with blue interior. 1973 450sl
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what brand was installed? how "deep" under the material did they install it? I have heated seats installed in every car I have upholstered, including both of my 107's, the seat covers are pretty thick and dense so it does take a while to radiate through but they do get warm. maybe the units installed just aren't any good? heated seats are the only heat [beside radiant engine heat] in my hot rod and I can drive comfortably in above freezing weather.
 

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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #7 ·
I have no experience with heated seats on the 107, but can you confirm that they are actually drawing the current you claim?
Yes I was with the Mercedes electrician and saw the current being drawn by the relay (under the seat) and the manual states that that should be the amp that should be drawn.

So the heater pads are receiving the correct amount of current. Also on second stage i.e. full heating double red, the system automatically reverts back to low heating i.e. 1 red light after exactly 5 minutes.

Theoretically if the system reverts to low after 5 minutes, it means there should be sufficient heating.

Any experience on other cars? It's the same technology as on the 126 and 124 cars. I cannot imagine such low heating (on double red) is normal



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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #8 ·
what brand was installed? how "deep" under the material did they install it? I have heated seats installed in every car I have upholstered, including both of my 107's, the seat covers are pretty thick and dense so it does take a while to radiate through but they do get warm. maybe the units installed just aren't any good? heated seats are the only heat [beside radiant engine heat] in my hot rod and I can drive comfortably in above freezing weather.
The pads were purchased from Mercedes. That's one area we are looking at but both seats are the same, so could it be that all 4 pads (2 per seat) from the factory are defect?

The pads were installed on top of the horsehair material. The MB tex cover has a spongy/cushiony material underneath each seam. So the pad sits between the horsehair and the spongy/cushiony material under the MB tex. But there is no possibility to install the heater pads above the spongy/cushiony parts of each seam. There's no space.

Mine takes time but I had the soft top closed last night, and with such minimal heat, I would not be able to drive it with say, the top down or window open.

Any idea what the temperature is of your seats when on full heat? How do your buttons operate?
 

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1989 560SL
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Yes I was with the Mercedes electrician and saw the current being drawn by the relay (under the seat) and the manual states that that should be the amp that should be drawn.

So the heater pads are receiving the correct amount of current. Also on second stage i.e. full heating double red, the system automatically reverts back to low heating i.e. 1 red light after exactly 5 minutes.

Theoretically if the system reverts to low after 5 minutes, it means there should be sufficient heating.

Any experience on other cars? It's the same technology as on the 126 and 124 cars. I cannot imagine such low heating (on double red) is normal



View attachment 2723657
Your 124 and 126 comment makes me think you might get a better response and information on one of those forums. 126 most likely. I have always been in Oklahoma, but since I started working on Mercedes-Benz in 1978, factory seat heaters were extremely rare up until the 1990s. I can’t say I ever saw a US 107 with a seat heater before the 1986-89 560 era, and then only a couple.
I‘ve had a US version 1986 560SEL for 25 years that has seat heaters. And I had a 1984 500SEL that had them. Both were the most fully optioned models we could get for the era. My 560SEL even has the Town & Country horn.
I recall the seat heaters in those 126 were tolerable. But nothing like modern heaters
 

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1996 SL500, former 1986 560SL
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Did the heater elements get installed directly against the bottom side of upholstery material or is there a layer of something in between? Even a thin additional layer will make a difference.

When I replaced the leather upholstery on my 560SL, the heater elements were in direct contact with the underside of the leather. It was a challenge to remove the old elements from the old upholstery and reinstall them in the new upolstery without stretching/damaging each individual "finger" of the element (it's a very snugg fit to fish each finger thru the upholstery).

I found it took about 3 minutes to start to feel the heat and probably about 8 min to get to a very warm full temp on mine (both original or new upholstery). I find heated seats newer cars seem to work much faster, but mine did work better than what you described.
 

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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #11 ·
Did the heater elements get installed directly against the bottom side of upholstery material or is there a layer of something in between? Even a thin additional layer will make a difference.

When I replaced the leather upholstery on my 560SL, the heater elements were in direct contact with the underside of the leather. It was a challenge to remove the old elements from the old upholstery and reinstall them in the new upolstery without stretching/damaging each individual "finger" of the element (it's a very snugg fit to fish each finger thru the upholstery).

I found it took about 3 minutes to start to feel the heat and probably about 8 min to get to a very warm full temp on mine (both original or new upholstery). I find heated seats newer cars seem to work much faster, but mine did work better than what you described.
They were installed right on top of the horse hair material and between the upper leather material and the element is a layer of cushioning (as shown on your attached photo). So the element is not in direct contact with the leather, but rather in contact with the cushion material attached to the underside of the leather. The elements are installed inside the backrest and the seat so two elements per seat.

When I had the seat covers removed, there was simply no gap between the leather and the layer of cushioning to be able to push the element through. But based on your experience, the element should be somehow pushed through? How did you manage that?

Do you have anymore photos of your heated seats? The one you attached is very useful!

Would you say the heating is sufficient enough to drive with the soft top down during winter months?


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.
 

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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #12 ·
Did the heater elements get installed directly against the bottom side of upholstery material or is there a layer of something in between? Even a thin additional layer will make a difference.

When I replaced the leather upholstery on my 560SL, the heater elements were in direct contact with the underside of the leather. It was a challenge to remove the old elements from the old upholstery and reinstall them in the new upolstery without stretching/damaging each individual "finger" of the element (it's a very snugg fit to fish each finger thru the upholstery).

I found it took about 3 minutes to start to feel the heat and probably about 8 min to get to a very warm full temp on mine (both original or new upholstery). I find heated seats newer cars seem to work much faster, but mine did work better than what you described.
How do your heater switches function? I noticed that full heat mode (double red on the switch) is automatically disabled after 5 minutes and reverts to low heat mode (1 red bulb on the switch).

Do your switches function in the same way?
 

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1988 560SL (California Model)
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Your 124 and 126 comment makes me think you might get a better response and information on one of those forums.
This ^^^^^^^ Betting the majority of the SL sales were California and Florida...not exactly known for cold climates. Probably had a post or two about seat heaters in the 12 years I have been on the forum but to be honest...can't remember any. Posting on the 126 forum is a great idea..
 

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1996 SL500, former 1986 560SL
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How do your heater switches function? I noticed that full heat mode (double red on the switch) is automatically disabled after 5 minutes and reverts to low heat mode (1 red bulb on the switch).

Do your switches function in the same way?
Sorry, I'm not 100% certain since I no longer have my 107, but I think they did function something like that after 5 or 10 minutes of full heat. It could have possibly been that the seat-back heater was disabled in the 1 red light position... but I could be confusing that with a different car.

After I removed the old upholstery, I did not think I would be able to re-install the heater elements in the new upholstery, but I did manage to fish each heater "finger" thru the tight space between the leather and the sewn-on padding on each of the seat bottoms and seat backs just like the original upholstery I removed. It was a slow and tedious process.

It took some trial and error, but I got my most efficient results by using a long piece of 1/4" dowel with a rounded end and a small hole to recieve a small-but-sturdy safety pin that could be woven thru the heater felt finger as shown in that picture. It took patience to go slow and not tear the heater felt or catch the fishing rod or safety pin in the tight space.

I suspect that Mercedes fished them thru with a long slim-but-strong rod with some sort of slim wide clamp (ie 3/4") on the end to grip the felt finger very securely. It did not apear that Mercedes sewed the original upholstery with the heater fingers installed (it would be very difficult not to catch them with the sewing machine).
 

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They were installed right on top of the horse hair material and between the upper leather material and the element is a layer of cushioning (as shown on your attached photo). So the element is not in direct contact with the leather, but rather in contact with the cushion material attached to the underside of the leather.


View attachment 2723711
.

I have torn apart some original MB heated leather seats, and the heating elements of the originals are inside the seat covers close to the leather, not under the padding (and just on top of the horse hair).

I have owned two euro SL with heated seats too. The 1979 280sl with heated fabric seats ( sold to @JN74SL ) were notably warmer than the 1985 280sl leather seats I have now. I now have sheep skins on top of my worn and cracked leather. I was actually about to swap the seats out with a set that has no heat in them because my heat wasn’t working at all. That’s when I realized the heating elements weren’t plugged in at all.

I can say that I’m not impressed, and can see why they were left unplugged in my 1985 280sl 5-speed. There is some warmth that I can feel, but it’s not hot like my 2006 Honda Ridgeline seats will get.
 

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1989 560SL
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How do your heater switches function? I noticed that full heat mode (double red on the switch) is automatically disabled after 5 minutes and reverts to low heat mode (1 red bulb on the switch).

Do your switches function in the same way?
All Mercedes-Benz factory seat heaters I have ever seen function in that way. 1980s thru 2021
 

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W126 1985 280SE RHD - R107 1986 420SL RHD
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Discussion Starter · #17 ·
Sorry, I'm not 100% certain since I no longer have my 107, but I think they did function something like that after 5 or 10 minutes of full heat. It could have possibly been that the seat-back heater was disabled in the 1 red light position... but I could be confusing that with a different car.

After I removed the old upholstery, I did not think I would be able to re-install the heater elements in the new upholstery, but I did manage to fish each heater "finger" thru the tight space between the leather and the sewn-on padding on each of the seat bottoms and seat backs just like the original upholstery I removed. It was a slow and tedious process.

It took some trial and error, but I got my most efficient results by using a long piece of 1/4" dowel with a rounded end and a small hole to recieve a small-but-sturdy safety pin that could be woven thru the heater felt finger as shown in that picture. It took patience to go slow and not tear the heater felt or catch the fishing rod or safety pin in the tight space.

I suspect that Mercedes fished them thru with a long slim-but-strong rod with some sort of slim wide clamp (ie 3/4") on the end to grip the felt finger very securely. It did not apear that Mercedes sewed the original upholstery with the heater fingers installed (it would be very difficult not to catch them with the sewing machine).
I am dreading having to get the seats removed again!

When I had the seats out, the upholster and Mercedes electrician could not see how the elements would fit in between the leather and padding. I personally could not see a gap in between. We therefore concluded there is no other place for the elements other than below the padding and on top of the horse hair i.e. there was no direct contact with the leather.

I just checked a W124 convertible with heated seats. Seat starts warming up within 2 3 minutes, and after 5 minutes the switch reverts to 1 red light. Despite it working far better than my 107, I wasn't particularly impressed by the level of heat. It does heat up but no where near newer cars. The W124 has been sitting in a warehouse for over 10 years so don't know if that has any effect on the elements. I imagine it wouldn't.

When you first removed the element from the seat, were they glued onto the padding? Were there any signs of glue on them? I am trying to figure out how to get this done before having the seats removed again.
 

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Discussion Starter · #18 ·
I have torn apart some original MB heated leather seats, and the heating elements of the originals are inside the seat covers close to the leather, not under the padding (and just on top of the horse hair).

I have owned two euro SL with heated seats too. The 1979 280sl with heated fabric seats ( sold to @JN74SL ) were notably warmer than the 1985 280sl leather seats I have now. I now have sheep skins on top of my worn and cracked leather. I was actually about to swap the seats out with a set that has no heat in them because my heat wasn’t working at all. That’s when I realized the heating elements weren’t plugged in at all.

I can say that I’m not impressed, and can see why they were left unplugged in my 1985 280sl 5-speed. There is some warmth that I can feel, but it’s not hot like my 2006 Honda Ridgeline seats will get.
Right, so the elements should be between the padding and the leather. I just don't see where the gap is that's why they were installed under the padding and above the horse hair. Were there any traces of glue on the elements?

I wasn't impressed either after sitting in a convertible W124 and checking their functionality. I assumed the heating would be sufficient enough to drive with the soft top down during cold evening drives.
 

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Discussion Starter · #19 ·
All Mercedes-Benz factory seat heaters I have ever seen function in that way. 1980s thru 2021
I noticed that today on the W124. And for how long does this 1 red light function stay on for? Does the relay under the seat switch the heating off completely at some point and/or switch it back to the 2 red light function?
 

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1989 560SL
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I noticed that today on the W124. And for how long does this 1 red light function stay on for? Does the relay under the seat switch the heating off completely at some point and/or switch it back to the 2 red light function?
I am 99% sure that the seat heater never goes back to a higher setting automatically. You will have to turn it off all the way and try to "reignite" it. I think if the system has a certain amount of heating in the element and wiring it will stay at the lower setting.

Funny story. I had a shameless social climber friend hanging at my shop years ago (in the absolute heat of summer) when a "civic leader" customer needed a ride to his office. Told the climber to take the leader to his office in the 1984 500SEL I mentioned upthread, in order to help him get some face time. He came back drenched in sweat. I had forgotten the driver seat heater was somehow stuck on high and would not shut off.
 
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