Anyone Know of a way to make the rear defrost more effective? It seems to work but very slownly and It cycles off before its totally defrosted. Are the little contacts on the window solderable? Do you need to replace the rear window if you want to replace the defrost heating strips on the window? Could that be the problem?
Thanks all

how cold is it? I think the rear defroster switch is on a timer, so if you have a lot of humidity in the car it'll be hard to defog all the way. if it's FROST on the outside of the window, and you are driving, it's REALLY hard to let the defroster handle frost. best to REMOVE The frost from the outside, and let the defogger system keep it free.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Well, now its not freezing yet but the two years Ive had the car its been very cold up here in the winter compared with most of you down south. usually a thick frost or freezing rain on the window.

t just seems weak on one or two particular strips. Most modern cars I drive can handle a good layer of ice or frost within 10 or 15 minutes of driving.

Permatex sells some copper defroster grid repair paint.

But, on my window that has the grid exposed on the inside the Copper grid lines appear solid but are actually corroded. The corroded spots in the pic are dark brown and the break the electrical connection.
(Someone replaced my Rear Window from one that came from a Junk Yard where it must have been exposed to the elements.)


Someone on our forum posted the below site:
Window defroster defogger repair grids
http://www.frostfighter.com/

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

My guess is that your MB is similar to mine. If I am correct, the comment regarding the repair of the wires already present is accurate. We live in Buffalo, NY and experience harsh winter weather conditions. My MB rear defrost is faster than the Honda, or any of our Chrysler or Ford products. My guess is that repair of the grid is more painful than replacement, but I suspect a good auto glass shop has the proper equipment / skill set to make you smile.

I'm no electrical engineer, but I wonder if a person couldn't use a transformer to bump the voltage of that circuit up to, say 24v? Of course, it wouldn't help if the grid is in sad shape to begin with.

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'82 300SD - Somewhere over 220k - Becoming reliable...

Nope, transformers only work with AC current. Cars use DC.

ninja edit:

DC-to-DC converter - Wikipedia, the free encyclopedia


^ New to me, never knew.

My 560 is sub-par also. But my wires are within the lamination of the glass. Not on the inside or out. The wires are so small they are hard to see. They also take a long time to defog or melt ice. My Mark VIII could toast a bagel if it wanted to. Both had a max time limit before automatic shut-off. I think around 10 minutes.

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car

I replaced the rear window on my 126 with a brand new replacement part - new grid, in other words. It's still quite pathetic and takes a long time to melt ice on a cold day. In Winterpeg on a cold -30C night I think you would see it take forever to melt ice.

Princess Auto and other "cheapo" parts places used to sell little warm air heaters that sit on the parcel shelf and blow hot air onto the back window - power it off the cigar lighter outlet. Just a thought....

I'll be damned, never knew such as think existed.. I stand corrected

Still, going to 24V may make the element turn into a busted fuse. I'm thinkin' extension cord... blow dryer.

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Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

The hot extension cord is exactly the effect this relies on. My gut says that if it doesn't work, there must be something to be repaired, but the coldest day I've ever had to deal with was 10F. That window exposed to sub zero is a hell of a heat sink. If the circuit doesn't get hot enough to melt ice, it can't get hot enough to melt the element! Maybe these northern types need a dual range element - a regular duty defrost and a sub zero mode. I'm just speculating, normal works excellent for me.

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'82 300SD - Somewhere over 220k - Becoming reliable...

does any one know what resistance the window wires are supposed to be? My thought is they have gone up in resistance to the point that they will not pass enough current to heat up. Prolly due to age. I get good voltage to the wires but no current at all.
I may try scraping the old stuff off and trying the Frostfighter....

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Brownie' 81 300D Auto
Engin'r.....

With the defroster on try reading the voltage from one terminal at the window to the other. Just in case there is an abnormal voltage drop. If not twelve volts or whatever the battery voltage is. There may be too much loss on the feeder wires and circuit.

Since it is reported they are not stellar performers anyways. Plus i never remember anyone reporting the available voltage under load back there.

My 80 240D has 2 wires that work, second from the top and second from the bottom. My case it is the deterioration of the grid wires. I have a replacement back glass and new gasket to install.

Our 85 300D has worked great for mostly the dew in the mornings and the frost we get, but we have no where the cold icy days as AZITIZZ gets in the cold Canadian winters.

In this case the 12V electric blower on the rear shelf as mentioned above would sure speed up the thawing.

One time on our 85, I broke the conection on the left side and was able to resolder it and works fine now.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works