Hi George,

This is something I actually tried once. Not on a 140 Volvo, but a mini van.

The metal film on my old one was not so much scratched away as "eaten" by some chemical process - I could see it. Only about 3 lines heated up. But I could not feel the difference. I figured it was probably some protective coating on the film got cleaned off the inside of the window. It was beyond metallic paint repair kits.

I wanted to check out the junkyard window before buying it. I had no idea what the resistance should be, and was aware that any low current measurements I could make with an ohmmeter would not reflect the warm resistance presented in operation.

So, I took an old bagphone battery in my toolbox and a magnetic compass after testing the idea on the old 3-line window. The little battery wasn't nearly up to the current, but for the twenty seconds or so it took me to scan the lines with the compass I was able to buy the window with confidence.

Sort of a fast-fading memory, owning a minivan.
--
Art Benstein near Baltimore

It may be that your sole purpose in life is simply be kind to others.