About a top third of my rear defroster is not working (5 horizontal lines from the top) on my 2015 C300, anyone with partially non working rear defroster? Since I never use the rear defroster, this may be a problem from production.

Yes! same thing, the power also rerouted to the bottom part of the defroster so it got super hot and actually burned my knuckle. Brought my car in for 40k service last week, they are replacing the rear windshield right now to fix the problem.

I noticed the same thing on mine! The top 3-4 rows of heating elements don't work. I was planning on mentioning it at my next service. I am contemplating just letting it be since I have no rattles or wind noise issues right now though.

I think they are not used for heating, may be for radio antenna.

I doubt it but will let you know after my appointment at the dealer next week. I just got my car worked on back in Nov but didn't notice it since I never use the defroster.

Yes, the lines on the top third of the rear windows are antenna lines. Only the bottom two-thirds of the window has the active defroster lines.

I also noticed this happening on our brand new C220d. Only had it 2 weeks, so figured it may have been failed from the factory.
It went back 2 days ago for some factory work (unrelated), but I forgot to ask bout it... however the loan car (also a W205) also does the same.
I'd already noticed that the lines that weren't demisting had vertical lines running between them, near the middle.
I've since read elsewhere that others have had it confirmed from their dealers that they are indeed radio antennas rather than heating elements.
Kinda bummed about it really, as I've already mounted the rear facing dash cam right at the top, and its view is blocked by the ice & the fogging inside on cold winter mornings.

Thanks all, will call the service rep before taking the car in next week.

Spoke to my dealer's service rep this morning and he told me to bring the car in for service since top portion of the defroster should also heat up. Stay tune...

they are antenna. not defrosters. evidence to support this, everyone's car does not heat up top of rear window. i doubt everyone would have this issue.

Thanks all, just got a call from my service rep after I dropped my car off this morning. He says according to the Tech, the top portion is for antenna and not suppose to heat up. What the freak??? Two service reps told me separately yesterday that the top portion should heat up so please bring your car in for service. I checked and double checked with them yesterday so I don't have to waste their and my time. Unbelievable!!

Lol service reps are usually not knowledgeable at all regarding the cars, well at least from my experience. Next time I suggest you ask for them to speak to a technician to confirm an issue rather than them just telling you.

np6345, they both claim they talked to the Tech and said it's not normal. Apparently they spoke to the Tech that does oil change or operate their car wash.

BTW, the paperwork says they perform diagnostic to the heating and antenna elements and compared the results with another C300; then determined that this is performed as design intended. Either they want to milk the factory or have no idea that this is normal or not. I'm still speechless.

I have had my car for just a week, and tonight I turned on the rear defroster and only the bottom 2/3 cleared up, so I'm suspecting it is normal.

I have a feeling I experienced the same thing today. How can you test it to see if its working? I don't know how to put a slab of ice on it to prove its not working..

the top 2-4 bars are all antenna. is normal.

I hope I don't have this problem as I have already had my share of problems.

Does your 5th line from the top have a break towards the right (passenger side)? Top 1-4 all have breaks along the lines.

Alright people. According to our shop foreman (who is also an MB master Tech of 35+ years). The lines on the top third of the rear window are ANTENNAE ONLY!!! I have attached a picture to show you exactly where the antennae lines start.


EVERYTHING above the BRIGHT RED LINE is NOT for window heating!!!! And yes, that happens to be about 1/3 of the rear window.