hello,

my 84 300 SD (w126) has a problem with the rear defogger, it only defrosts the top 1/3 of the rear window. How do you go about diagnosing the problem? The light in the front console comes on and stays on for 10-20 minutes but only top 1/3 gets defrosted. The elements appear intact, but is there anyway to test them?

There has been a post about this in the diesel section started by silverbullet...
The rear defroster of the cheaper mercedes models can easily be tested; the W126 has a different type of rear defroster. Mercedes uses a defroster with very tiny sinus-waved elements in the more expensive models and these elements are stuck between the different layers of the rear screen.
If the top layer only gets defrosted, there is something wrong with the rear defroster itself. The lower 2/3 part of the elements is disconnected from the power (left-side) or ground (right side) connector.

This will be quiet difficult to repair; you can have a look at the connector side to see if there is anything wrong, but I think it will not help you...

Maybe someone else on this forum can give you a more positive answer...

good luck & greetingz,

My rear window is also only defrostning the top 1/3 and I apprx. 4-5 lines lower down (the lines on my window are with 5mm distance). I think that the top 1/3 defrost because of the warm air coming from the front of the car.

My window is also really white on both sides too, and if the lines are stuck between the different layers I have to buy a new rear window...

Does someone know if I can order a tinted window for the rear and side windows? And what colors can I choose from? smoke, blue, green...?

/Patrik

Do you have a milky white substance on the bottom corner of the windows? If you do, it is most likeyly the connections are rusted or corroded. There is no real answer to this problem but, it is common. I have similar problem.

Yes,

I have that whitish foglike appearance at the edges....so does that mean I'll need a whole new glass for the rear (any ideas how much it'll run?)

The solution turned out to be a new rear glass in case anyone else is having this problem....pretty expensive repair, but I also found that I was leaking water around the seals causing part of the rear frame at the bottom of the window to rust (4 inch part of it)....got a body shop to repair it for $300

Now everything works well again!:D

I'm glad everything works OK for you now. I checked the price for the glas and work, it would cost me 1.000 USD. :( Not cheap. The rear window for coupe are probably more expansive than sedans/combi's. I will fix the oil leak first though, another 1.000 USD. :mad:

Happy new year to You all! /Patrik