No rear window defog

gregk1 · 05-07-2002, 05:55 AM

My rear window defog does not work on my 76s. The defog in the mirror works and the light in the knob comes on. The fuse is good Any ideas on this problem?? What tests could I do to find out why it is not working

T Bird · 05-07-2002, 06:14 AM

Greg
On cars of your vintage, often the defroster wires on the glass deteriorate to the point where breaks develop. Check for 12 volts at the spade connector on the rear glass. If you have power there, you've got breaks in the defroster wires. If you don't have power there, work from the switch back checking for voltage. There is a two-stage relay in the engine compartment of my car (72). Yours may be there too. This could also be the culprit.

Good luck.

gregk1 · 05-07-2002, 06:30 AM

Ok I will do that this afternoon Thanks John

Targa77 · Targa77's Garage

My car had the same problem. Reseated the relay and cleaned all contacts on the rear left. Put dielectric grease on all contacts. Now it works like a champ.

1bar · 05-07-2002, 05:10 PM

I had the same poblem, but wasn't as lucky. The traces on the rear glass were all broken - had to replace the window to get the defroster back.

Parts Heaven, or one of the other reputable auto recyclers can get you a correct window from a wreck with (mostly) working heater elements for 1/3 the cost of a new one. If you're not on a budget, you could consider going for a new one.

One interesting thing I noticed. I got the glass from an '83 SC to put in my '77. The newer glass is thinner, or something, than originally in the earlier cars. The outside road noise now gets through into the cabin much more than it did before. Especially noticeable when a truck pulls up next to me at a stop light.