re: Window Defroster

["Giller,Bruce C." <bgiller@domain.elided>]

George,
	My '73 GTV has heated rear window and I was trying to get it to work a
few months back since we get snow/sleet/ice here in the DC area every
once in awhile and I wanted to be ready for winter ahead of schedule.  I
also get a fogged rear window when it is damp outside (yes, my GTV leaks
at the lower front corner on both doors - even with a new door seal on
the drivers side).  As with your car, the defroster switch worked, had a
good ground on one side of the window and 12v on the other but no
heating of the elements.  The 12v window clip was no longer attached to
the window so I thought this was the problem.  But looking at the
condition of the heater 'lines' on the back window, I noticed that there
were segments where the conductive material was missing.  I had bought
some 'copper paint' for the Spiders hard top rear window defroster and
it worked well to restore the circuit on two of the lines.  I thought I
could use the same on the GTV.

	Got out my trusty voltmeter, made sure that the 12v clip was conducting
to the window and went to find the electrical gaps.  You find them by
turning on the defroster circuit and then testing the voltage drop along
a heater line.  The further you get away from the 12v source, the lower
the voltage - when it goes from some voltage to no voltage, that is
where the gap is located.  Well I found that there wasn't any voltage
along any of the lines nowhere!  Then I tried a continuity test on each
line with the ground and 12v supply wires disconnected - no continuity. 
Even with the probe ends only millimeters apart on a single line, I
couldn't get any reading.  My conclusion is that the heater lines no
longer function as electrical conduits because of age, sun, heat, cold,
etc.  In fact the lines would flake off easily.  And I didn't have
enough copper paint nor the patience to paint a whole new grid on the
rear window.  Me thinks that you may have the same problem.

	However there is a conductive epoxy that I got long ago from a plastics
house for around $70.  I used it to reattach the radio antenna line back
onto the connection on the front windshield.  Work well for many years
but just recently has broken off again.  Another list member reconnected
his with a soldering gun - he was more daring than I.

	The big question is, does anyone restore old defroster grids?

	Bruce

 
> Being that my car ('74 GTV) isn't water tight, each time I get caught in the
> rain, I go through a ritual to dry out the carpets and floor mats.  This process
> inevitably fogs the rear window.  The rear window defroster switch works; there
> is power all the way back to the window; and the window is grounded to the chassis.
>  The problem is that the connector for the hot lead is no longer attached to
> the foil on the window.  I've been afraid to touch it with a soldering iron
> for fear of cracking the window.  Is there a conductive epoxy or othe glue to
> use and where can I get it?  Lots of glues tell you they are non-conductive,
> but I haven't found one which claims it in the positive.

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