Rear defroster no longer working?

[Coupester]

This question pertains to an 85GT.

I was wondering if anyone randomly had their rear defroster cease to function? I bought my 85 GT from a friend in June, and the defroster has not worked since I bought the car. I was very jealous when my friend acquired the 85 GT and he let me take it for a test drive a while back (long before I acquired it), and I remember specifically using the rear defroster and how well it worked. When I flip the switch for the rear defroster, the light on the HVAC controls illuminates, however the rear defroster does not engage. All my fuses are fine, the car has no electrical problems at all, and everything else ( I mean everything) works perfectly.

Let me know if you have any ideas for me!

thanks,
Chris

[PNY XPRS]

check the two connectors to the window itself. They use a metallic paste to glue those to the contacts on the defroster and that paste becomes VERY brittle and can lose contact very easily.

[Coupester]

thanks! I will check that

I refuse to let this small problem detract from the car's perfection!

[795.0pacecar]

Hey I dont even have rear defrost lol.

[tim73]

I have like 4 lines that work...and the thing is they are all spaced out. Weird

[Anonymous]

There's a timer unit that controls the on/off time of the defroster. Its probably got bad contacts. Should be able to get a new one.

Check your connections to the actual window coil too, mine were broken.

Later,
Aaron

[Kevins89notch5.0]

Hell, on may car, it looks like someone took a knife, and simply cutt the wiring harness inbewteen the hatch, and the body. Yet another mystery about this car. I will be rehooking up those wires this spring.

[Johncr85GT]

I ran across this thread, my rear defrost does the same thing, I checked the obvious, and was wondering what "coupster" came up with. Or any opinions from others! I suck with wiring, any easy fixes?

john

[50 Proof]

was there any tint on the window? If the rear window was tinted and then someone later removed the tint, sometimes the defroster lines get removed with the tint.

[DELETED]

Mine doesn't work either... the contact came off. I'd fix it, but it's almost summer

[Johncr85GT]

was there any tint on the window? If the rear window was tinted and then someone later removed the tint, sometimes the defroster lines get removed with the tint.

there was tint, Ipulled it off, all the lines on the glass are intact. It didn't work when I got the car.

John

[50 Proof]

my 86 GT had tint on the windows when I got it. I pulled the tint off and the defroster stopped working after I pulled my tint off. Even though all the lines were still on the rear window, the tint pulled off sort of a layer of the defroster lines, leaving my rear window defroster broken. I have another hatch lid with a rear window though, so I didn't care.
You can still physically see the defroster lines on my window, the defroster truns on too, but the defroster lines don't work anymore.
Any time you remove tint off of a rear window with defroster lines, you are risking damaging the defroster lines on the winow. There isn't a single tint shop I have talked to that will guarantee a working rear window defroster if I pay them to remove my tint.

Maybe possibly someone had tint on the window before but removed the tint and had it replaced with new tint? If your convinced your lines are not the issue, i'd check the wiring going to your hvac controls. If the hvac controls have ever been removed, maybe a wire yanked out of the connector for the defroster?

[PNY XPRS]

yep.. that's the problem. The rear defroster is in 2 parts, a backing "grid" that adheres to the glass and the conductive traces that follow the "grid". When you remove tint the conductive material comes off with the tint. All the wiring is intact, the power is there, but there's nothing to carry the current through the defroster.

If you ever see someone's defroster that has a few lines in it that don't work, you can look very carefully at the traces and see gaps in them.

When I had my rear window re-tinted after Alabama changed the tint laws, I lost about 5 lines on my defroster. When that new tint faded and turned purple, I removed it and the rest of the line with it.

[cjwanner2000]

so, what nobody seems to be mentioning here is how do you fix/replace the lines?

[negusm]

Not exactly for Mustangs but probably not a bad article to get you started:

http://www.ifsja.org/tech/electrical...r_repair.shtml

You can buy the conductive paint and reapply it.

-Mike

[cjwanner2000]

good instructions, thanks. isn't there some kind of grid that you can buy to put over your existing grid? the one in my bronco has about a zillion breaks in it. anybody heard of or tried those grids?