Rear defrost suddenly stopped working - 2011 Fusion

[Klutch9]

As the title says, the rear defrost quit working in the last few weeks. I tested the 40a fuse and the relay that feed the circuit, and both are good. The button on the dash also lights up when pressed. But no part of the heating grid works anymore. There are no breaks in the grid anywhere. I can’t imagine what else would cause it to quit. I know that there are tabs in some place soldered on so that the wiring can attach to the window grid and complete the circuit, but I can’t imagine why these would break. Car barely gets driven anymore, and hasn’t had any accidents, recent work, etc.

 

[Rand]

any way to test for power at the rear window?

 

[Pelican]

As the title says, the rear defrost quit working in the last few weeks. I tested the 40a fuse and the relay that feed the circuit, and both are good. The button on the dash also lights up when pressed. But no part of the heating grid works anymore. There are no breaks in the grid anywhere. I can’t imagine what else would cause it to quit. I know that there are tabs in some place soldered on so that the wiring can attach to the window grid and complete the circuit, but I can’t imagine why these would break. Car barely gets driven anymore, and hasn’t had any accidents, recent work, etc.

It may have come unplugged, check it!

 

[Number_35]

One side of the grid should be at (nominally) 12 VDC, and the other side at ground. The midpoint should be at approximately half voltage. A break in any grid line will show full voltage (12 V) up to the break, and 0 V on the other side.

 

[JavierH19]

check the power going out of the plug. if there's no power investigate the fuse.

 

[Klutch9]

Well, I pulled one trim piece off to check the connection on the driver’s side… sure enough, the solder had failed and the metal connector was just dangling! I guess 11 years of heat cycling will do that. I added some solder to the connector, pressed it against the contact point on the window and applied pressure from the hot soldering gun until the solder flowed. This took WAAAAY longer than I expected… probably because the ambient temp was about 20 degrees F. The window, as it turns out, is a very large heat sink and takes awhile to heat up haha. I kept applying heat for awhile and then shutting off the gun, trying not to heat the window too much (didn’t want a crack), only to find that the connector was super hot but the window was still cold. All good now though.

 

[michaelluscher]

I'm just kidding, glad to hear it was a relatively easy fix

Seems this happens on a few late model Ford's, wonder if it's low lead solder drying out and or cracking?