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Discussion Starter #1
In 1970, GM offered an unusual and very rare rear window defog option. It basically consisted of a vent and fan in the center of the rear package tray of the car. I have been wanting one of these since I discovered them last Summer. As I said, it is very rare and somewhat difficult to find. In fact, Ebay is about the only source for one.
I have a different idea that borrows from GM's original design. All Novas have a square and round hole stamped in the sheetmetal in the center of the package tray for this option. What if I installed two 2" round vents from a conversion van or and aftermarket AC system on the rear package tray? I could use 2" heater duct hose and mount a fan remotely. This would allow me to go one better than GM because I have found a way to route heated air to the rear glass. I can purchase a 12 volt heater with fan for $12.99 at Harbor Freight or from JC Whitney for $16.99. The vents and vent hose should be dirt cheap at Pull-A-Part. I'm also thinking about a rear defrost switch from a late model car for the dash. I'm still in the planning stages on this but I think I'm going to try it in '06.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=36711

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2002890/showCustom-0/p-2002890/N-111+10201+600002307/c-10101
 

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i have a defrost unit in my shop out of an old Dodge Monaco (i think) it's a 6x9 speaker install unit with a blower motor on it...

i was gonna install it in my project... would you like a shot of the unit i have ???



John (trying to help) :)
 

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the Flyer said:
would you like a shot of the unit i have ???
Please NO, this is a family oriented site ya know. So no pics of Flyer's unit!!!

But go ahead and post a pic of the defroster!!
 

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i guess i should reword that :rolleyes: :eek: :eek: :eek:


here ya go, a little dirty, been sitting for close ta 20 years waiting on the Flyer project...



 

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OtheR GM models

Next time your at your Pull A Part, take a look around at some of the other GM Models (Pontiac, Buick, Olds) from that era, they all basically used the same rear window defroster, and grab the switch with it, if its still there.
 

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Discussion Starter #8 (Edited)
the Flyer said:
i have a defrost unit in my shop out of an old Dodge Monaco (i think) it's a 6x9 speaker install unit with a blower motor on it...

i was gonna install it in my project... would you like a shot of the unit i have ???



John (trying to help) :)
I appreciate the thought but I think I'm going to stick with the rough draft I have now. I'm thinking I can work this using very little truck space. I am also kind of big on the idea of having heat as an option. My big concern right now is how much airflow one of these aftermarket heater/fans will move. If it is very little, I may need one for each vent.

would you like a shot of the unit i have ???
...And you can keep them shots of your unit to yourself. Don't make me bust out some old Ray Stevens music.

http://www.songagram.com/Have_A_Nice_Day/TheStreakwav.htm

 

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Discussion Starter #9
SparkysSS said:
Next time your at your Pull A Part, take a look around at some of the other GM Models (Pontiac, Buick, Olds) from that era, they all basically used the same rear window defroster, and grab the switch with it, if its still there.
Thanks for the input. I'll definitely keep that in mind. I was pondering having a three position switch so I would have the option to just run the fan alone or the heat with the fan.
 

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tpinovaII said:
Thanks for the input. I'll definitely keep that in mind. I was pondering having a three position switch so I would have the option to just run the fan alone or the heat with the fan.

Just a thought but wouldn't the fan with heat draw more current than just the fan did. Possibly the original GM swith for the fan type defroster might not be able to handle enough current....you might want to look in to using a relay to handle the current and just use the switch the operate the relay...just thinking out loud...I really like the idea of the rear defrost...BTW my 69 cutlass had the rear defrost fan(no heat) and it actually worked pretty good IMO.:)
 

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Discussion Starter #11
69NovaSS said:
Just a thought but wouldn't the fan with heat draw more current than just the fan did. Possibly the original GM swith for the fan type defroster might not be able to handle enough current....you might want to look in to using a relay to handle the current and just use the switch the operate the relay...just thinking out loud...I really like the idea of the rear defrost...BTW my 69 cutlass had the rear defrost fan(no heat) and it actually worked pretty good IMO.:)
That thought already crossed my mind. My battery is in the trunk so relays do make a lot of sense.
 

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I have one of the original fan units (never thought they were all that rare, shows what I know). The two speed fan is not a 2 speed fan. The switch controls the speed. There is a large ceramic resistor for the low speed the no resistor for the high speed.

If you would like pics of the original set up let me know.

--Tom
 

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TPINovaII: Scrounge around the yards for a 4th gen that has the rear window defogger that you described. Good points are that you could probably find one with the switch, complete wiring harness, fan assembly and stock grille. The only complaint is that rear seat passengers may not like cold air on the backs of their necks.
 

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I thought one of the cars I bought had a in the glass wire kind of defroster, but later I found out it was a stick on kind. You could feel the bumps when you ran your hand over it. I think it was JCwhitney who sold a kit to do this at one time, but I'm not sure if they still do. This could be an option if you are just looking at having a rear defroster.
 

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Discussion Starter #15
I brought the mesh package tray from Year One and their jute padding underlay. The package tray has never really layed flat in the middle like it is supposed to. I am thinking that after I install some type of vent in the middle of it, it will also solve that problem so I have an alterior motive for the fan idea. Since I am not a big fan of the cold, something to put heat in the car a little quicker appeals to me as well.
 

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How did your defrost adventure work out. flyer Id like to see that defrost picture again if you still have it.

My car was originally equipped with a rear defrost but being young and dumb I didn't like it ... so I ripped it out. Oops. I also didn't think it worked that well

bought one of the jc whitney kits (electric wires) ... but never installed it or really looked at ... anyway was just thinking about defrost again and I thought I would bring the thread back. One downfall I have seen with them ... again haven't looked at mine ... is the wires are large thick and ugly.

Would love to see something that stuck on the glass ... would probably help with the back windows of wagons.

I have one of those cheapo jc whitney heaters but I think it sucks (no particular reason) and they would suck a lot of juice.

arndog
 

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Discussion Starter #17 (Edited)
How did your defrost adventure work out.

arndog
Like many of my other projects, it got moved to the back burner. The company I am working for has apparently decided I can do the work of three people.:eek: I have been working 12 to 16 hours per day and often seven days a week. Based on what others have told me, I have decided that I would want a factory defogger. It's actually more for the cool factor of having rare option than for function. (Normally, I am a form follows function kind of guy.) It just seems like a good fit since my car now has EFI, AOD, AC, power leather seats, cruise control, & etc. (Or maybe I am just running out of places to add things to the car.)
 
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