Would anyone happen to know the volts for the rear window DEFROSTER??

Probably 12 volts but you need to state the year and model of the car.

Here you go. 120 VAC 3 phase from a separate alternator, see description and schematic.

http://vintage.mitchell1.com/PClubData/chassis/del76/V2D764060.pdf

The Ford schematic probably isn't relevant, but it is interesting.


If we're talking about a vintage Mercedes, with just one alternator, the rear defogger works on 12V like everything else.

<< Post adjusted due missreading of the intent of above post , however this makes post 6 kind of hanging out there >>


There are other cars with higher voltage defrost too.

The W222 has a 42 volt front windshield.

" The windshield heater control unit actuates the heated windshield with U = 42 V "

http://www.benzworld.org/forums/attachments/w222-s-class/1278746d1420959750-how-enable-electrically-heated-windshield-w222-w222-heated-windshield-function.pdf

You need a new hobby. A reasonble response might be, "what car are we talking about?" Especially because he's new here. Instead, you tell him about the rear window on the millennium falcon.

95 E300D

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12v

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I remember the 120 V heated windows in the '70s Fords.

I also saw an article in IEEE Spectrum a few years back about MB pioneering the use of 42 V dc bus in cars. The idea being to remove all engine driven accessories (except the alternator) and run them electrically.

One of the benefits of this is that the air conditioner does not die at a red light with the obnoxious auto start stop system.

Ok back to the OP's point, unless he has one of the brand new MBs then most likely he has 12 V across the window. From the days of the 123 there is a spring loaded rocker switch that sends voltage to a relay behind the dash (123) or in the fuse case (124/126). The relay has a latching circuit and a timer. The control leads from the switch to the relay are tagged E and A for Ein (on) and Aus (off). No I don't speak German but I worked for a huge German company for many years so I picked up a few words here and there.
From the relay the voltage goes to the rear window. It enters one side of the glass, and on the other side there will be a brown wire which goes to ground. There will be 12 V applied across the glass.

With the defroster on, take your meter and probe across the runners at the left and right sides of the window. If you have 0 V it is one of two things. Either you have no voltage at all, or there is voltage going in, but no ground, so both sides of the glass are at 12 V because no current is flowing, and your meter reads zero. Try metering each side of the window to a known grounded point on the car. If you find 12 V between one side of the window and the good ground, then the grounded side of the window has lost its ground.

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I miss read post 4 thinking the Ford system was labeled as not interesting when you posted that it actually was interesting but not relevant. I've adjusted my post accordingly.

The "Serracin alternator" in the Ford schematic refers to a company that makes heated aircraft glass and I'd bet they built for NASA at some point.

Very much appreciated!!

Well the problem is that the defroster is already removed, the tint attached toasted and the grids were removed I have no way of finding the Volts and I also need to find out the amps
It's a 1995 e300D

Some MB cars use fine wires embedded between the layers of glass. Shine a light and or put white / black paper to gain some contrast and see if there are thin wires. ( Typically rear glass is single layer tempered with a heating grid painted on. MB sometimes uses 2 layer glass like a windshield, )

The larger question is what are you trying to accomplish? Knowing could help formulate answers.

I need to figure volts and Amps I want to replace the defroster grid with a new one from frost fighter.com

It is a 12v defroster, standard surface deposited type, if it's been removed by a tinter it is a shame, but one of the risks when one cleans the inside surface with a razor blade.
Are you looking to install an aftermarket one and looking for max. allowable current draw (are those still available?)? If so, I suggest looking at the capacity of the fuse feedijg it, if there are no other significant draws on that circuit/fuse then go no more than 66℅ of fuse capacity for a constant load, provided the wire feeding it is adequately sized and the relay is adequately sized (often relays have max. current listed on the outside).
Another possibility is looking at the Electrical Troubleshooting manual for any 124 sedan, it might list the normal current draw for troubleshooting purposes.

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