Is there a way to test defroster lines on rear glass, without power to it? Every time I go to junk yard and buy a rear window, when I get it home the defroster wont work or a bunch of the lines are not heating. Tried those repair kits, but they are too hard to try to get same size line plus it looks bad. If I good test the lines bfore I purchase this would save me money and headache's.

 

The defroster lines are part of a big resistor, so it is kind of hard to test each one. If you hold the probes of an ohmmeter about an inch apart and run them along each line, you should be able to spot a break if the resistance suddenly goes very high.