Hey everyone, I’m new here. I have a 98 Blazer With a rear defroster issue. The rear window will not heat up. It has power, it has ground, the grid lines are good, the heated side mirrors work and get warm, the timing circuit does what it’s supposed to do. The 30amp fuse is good and the relay is good. Everything is working except the rear glass will not heat up. Anyone have any thoughts?

 

If you know the circuit wiring to each side of the rear window is good, then perhaps the metal traces on the inside of the window were damaged? I had this happen to one of the traces on my window. I'm guessing it was damaged by something I had put in the back of my Blazer.

Have you measured the resistance between each side of the metal traces on the inside of the rear glass to check for continuity?

What would be odd is that they all might have gotten damaged at the same time. You might have to take a close look at them.

 

It’s interesting that you suggest that all of the lines went bad at the same time. The technician at my local Chevy dealer suggested that perhaps the window itself has had its day and needs to be replaced. Is that possible?

 

I think it is unlikely but it is easy to check with a multimeter.