Adding rear defrost?

[Mustang Kid]

Since my 82 mustang hatchback came from florida, they didn't have a need for the rear defrost option. Now that the car is in oregon, it kinda sucks trying to drive in the mornings and at night with the windows fogging up.
I have a mustang hatch with a good rear defrost window in it, but the hatch itself is kinked and warped really bad.
Carefully cutting out the windows will be a task but I know my dad and I can do it, but what else do I need to get the rear defrost to work? Wiring diagrams? I have the switch in the dash already too, and a body wiring harness out of an 84 GT that had it(no dash harness though).


Thanks in advance for any replies!

[RED 78']

I did this. Was not hard to do.
Click on the pic for the larger version of the wiring diagram.

[boboli]

http://www.frostfighter.com/index.htm

I am going to order a replacement defroster from these guys, since mine was ruined when I removed the tint.
Maybe save you some time or money or headaches

[BMW Rider]

Ironically, my 79 coupe has the rear defog on it but I may delete it as I have no plan to ever run the car in cold conditions. It all depends on if I can find a nice rear glass without the grid, not sure how well one could scrape the grid off the existing glass or if that would just make a big mess.

The dash harness would have the majority of the wiring you need, but you can probably run those in yourself. There is the relay of course and the power feed from the fuse block. You could run a separate fuse if you don't have the terminal in the block for that circuit. Rear defrosters draw significant amperage so the wiring is typically fairly heavy gauge.

[Dean_T]

IIRC the wiring is all separate from the main harness and the power feed is from a massive yellow wire which terminates at the battery side of the solenoid. There is a fusible link between the yellow wire and the terminal. The wire which feeds power to the rear window grid is a large gauge grey with yellow strip wire.

[IDMooseMan]

Ironically, my 79 coupe has the rear defog on it but I may delete it as I have no plan to ever run the car in cold conditions. It all depends on if I can find a nice rear glass without the grid, not sure how well one could scrape the grid off the existing glass or if that would just make a big mess...

Honestly, this is one of those situations where, IMHO, "I'd rather have it and not need it, than need it and not have it."

If you have rear defrost and don't need it, there's no sense in messing with it. My Ghia has rear defrost and, IIRC, the two wires connected to grid can be "unplugged" for rear window removal. I'd leave the wiring in the car, replace the rear window with a window you're happy with, and store the "defroster" window for future use, if needed.

[BMW Rider]

Honestly, this is one of those situations where, IMHO, "I'd rather have it and not need it, than need it and not have it."

If you have rear defrost and don't need it, there's no sense in messing with it. My Ghia has rear defrost and, IIRC, the two wires connected to grid can be "unplugged" for rear window removal. I'd leave the wiring in the car, replace the rear window with a window you're happy with, and store the "defroster" window for future use, if needed.

If my car was going to be anything resembling a stock Mustang, I'd certainly leave it in. However since this is a stripped down bare bones just barely street legal autocross car, the rear defrost will almost certainly never see use. Since I'll all ready be adding and subtracting wiring from the harnesses and rebuilding them with only the needed circuits, I figure I may as well eliminate the rear defog wiring too.

[Sinister]

If my car was going to be anything resembling a stock Mustang, I'd certainly leave it in. However since this is a stripped down bare bones just barely street legal autocross car, the rear defrost will almost certainly never see use. Since I'll all ready be adding and subtracting wiring from the harnesses and rebuilding them with only the needed circuits, I figure I may as well eliminate the rear defog wiring too.

leave the wiring in it, even though you dont need it, I do still keep it, mabe tomorrow or some where down the road, you find a nice glass that have a working defrost and swap it over ?

[fgross2006]

IIRC the wiring is all separate from the main harness and the power feed is from a massive yellow wire which terminates at the battery side of the solenoid. There is a fusible link between the yellow wire and the terminal. The wire which feeds power to the rear window grid is a large gauge grey with yellow strip wire.

Reviving this thread. Im adding a stock rear defrost setup to a car that never had it. Its an 84 vert.

I have the stock wiring, stock heater panel, NOS defrost switch. I keep reading theres supposed to be a relay and timer.

Is the relay the timer or is there 2 separate components?

I searched and cant seem to find any part number for a defogger/defroster relay. Would a fuel pump relay function the same way in this set up?

[RED 78']

If you looked at the page I posted, it tells you everything you need to know, and answers all your questions.

[fgross2006]

If you looked at the page I posted, it tells you everything you need to know, and answers all your questions.

It doesn't give apart number for an 84 and it doesn't show how the replay wires into the rear defrost grid.

[RED 78']

You need a lesson in reading comprehension.

http://study.com/academy/lesson/how-...rehension.html

Without typing exactly what it says on the page, I do not know what you want to know that is not already printed right there in front of you.
You questions are answered multiple times on that page. You already have the part, NOS, so you must know the part number.

[fgross2006]

You need a lesson in reading comprehension.

http://study.com/academy/lesson/how-...rehension.html

Without typing exactly what it says on the page, I do not know what you want to know that is not already printed right there in front of you.
You questions are answered multiple times on that page. You already have the part, NOS, so you must know the part number.

First, I don't see on that page where it gives part numbers for the relay/timer.
Second, the NOS part I got is the defrost switch, which is not the relay or timer
Third, I like FEP because everyone here is always either helpful or supportive, then there's the occasional rude prick like you. Very rare like a unicorn but occasionally there are sightings.

I bumped this thread hoping Dean would reply back because unlike you, dean is always a standup guy and never condescending. Your attitude is inconsistent with the culture of this forum. Feel free to ignore any future postings by me in this or any other thread. I got no time or interest in being insulted.

I suggest you brush up on your own reading comprehension and re-read the rules to this forum, paying close attention to rule number 2

http://vb.foureyedpride.com/showthre...ISIONS-12-2005