Well, I have finally come to the conclusion that my rear glass heater

isn't working.

at first I thought "maybe it just isn't very powerful", but now I must

admit that it doesn't do its job, much less heat the glass ;-)

here's what makes this interesting from my point of view:

the element gets power.

the element is continuous electrically.

the element has no visible damage.

the rest of the circuit checks out logically as well.

so, my question is this:

why is it that, even though it appears to work, the damn thing

doesn't get hot?

I know what sort of reply I'll get, Don Foster will say "resolder it!",

and most others will tell me to "get the little paint kit to fix the

traces".. I'm not looking for those responses, I'm looking for one man..

the man that knows these things inside and out, the man that designed

it into my wagon!.. he must have a Swedish name, of course. so,

help me out here. I don't know any Swedish names.

(and for those of you that have read my other posts)

jack is getting cold! soooo cold! he can't see out the window!

I'm surprised no one mentioned deterioration of the elements. Not breaks, not bad grounds, but slow disintegration of the conductive deposit and its binder from UV exposure resulting in higher resistance, presuming you can find mere open circuits without help. I mean, once you determine you have roughly 6 volts near the middle of all the lines you need to measure the current and compare to the 12 amps (the green book says 150W) a new one would draw.

I really wish there was some other respectable approach to fixing beside replacing the glass.

> the element gets power.

But what about ground?

> the element is continuous electrically.

Even if only one element is conducting, you will get continuity from one side to the other.

> the element has no visible damage.

The damage does not have to be visible.

You should get an evenly decreasing decreasing voltage along each element as you go from the power side to the ground side. ie halfway across the voltage should be half etc. If the voltage jumps from 12V to 0V at any point that element is broken.

"the element is continuous electrically"

Let's study this one a bit....how many ohms for the element?

I'm not sure what it should be....but I thought I would ask...now mind you I'm not even one bit Swedish...but hell some damn Italian guy was good at electronics....Marconi...oh he was an RF guy!!

Anyhow, record the ohms. Then have Don email you Ohm's law and I'll tell you a bit about Dr. Watt(son) VxI=W.......as the other fart smellers...I mean smart fellas say...it don't take much or you be smokin cracked glass faster that you can "Richard Pryor"...

I just design them, I don't fix them!

Good luck!

One question: "the element gets power" Did you check for power with the element connected or disconnected?

High resistance connection anywhere along the 12 volt supply line or bad ground connection can still show 12 volts on your meter with the element disconnected but when the load is connected it can drop to 0

BTW It will not heat the glass to the extent that you could feel with your hand but I assume you are aware of that.

"...sort of reply I'll get, Don Foster will say 'resolder it'..."

Now, now.

The glass doesn't get hot. The defroster only needs to warm it by a degree or three to eliminate condensation. So if you're evaluating by feeling for heat, you mighta fooled yourself.

"...the man that designed it into my wagon..."

Yeah, well, Sven also designed the blower motor and tailgate wiring and fuse panel. So his relay was clicked.

With the defroster on, make several voltage measurements relative to a known-good ground. One side of the grid should measure 12 volts, the other side should measure 0 volts.

If you get 12 at both side, the ground (perhaps the entire tailgate ground) is faulty.

If you get 0 volts at both sides, the wire supplying current to the grid is faulty (probably in the hinge harness).

Next, using a very sharp needle probe (maybe using a needle) measure the voltage along one stripe element in the grid, going from one side to the other. You should see a decreasing voltage as you progress across the window. If so, then the element is working. If instead, you continue to see 12 volts and then a sudden drop to 0 volts, you've just moved your needle probe across an open (break) in the element. Using a magnifying glass, examine the element for a microscopic break or tear. Often, adjacent elements will be broken in the same place—something slid down the window, tearing all the stripes.

"...he can't see out the window!"

Join all the other happy folks driving at 75 and chatting on their %#@*&% cell phones. They can't see out the window, either. But that doesn't stop them.

Don Foster (near Cape Cod, MA)

couldn't have said it better myself. I would add, on a wagon, the ground piggybacks on the rear wiper ground, which sometimes comes adrift. Also, wagonwise, if the hinges are the newer design with ground wires through them broken, that could be your problem. That tends to show up as a variety of troubles- intermittent lisence plate lights, feedback to the defog switch, etc.

Good point. On all my wagons the internal ground wire (internal to the hinge) was broken, so I ran an auxiliary ground wire. It goes from a convenient place near the wiper motor, through the hinge, and connects under the headliner.

Don Foster (near Cape Cod, MA)

I would think the problem is that it will measure continuity when cold but maybe some thing opens up under load. useas volt meter or test light. Clip one lead to the power lead on one side of the window. Then run other test probe along each trace from side to side. You should read zero volts near one side then up to battery voltage on the far side with no sudden jumps. If this is a wagon suspect the wires that bend when the tailgate is opened. For sedan and wagon check howthe wire is attachd to the glass. These fitting oftem work lose over time and do make good electrical contact.

Bill D.

ps be careful with the probe not to scratch through the baked on traces on the glass. Any chance there is a foil decal on the traces to short them out?