[Formulabruce]

An option nobody cares about, but look at this, TWO separate switches to run the rear defrost, 1970..Formula 400 One is ON-OFF, other is speed of blower. I never knew this.. I have not taken this apart yet to see the wiring etc...now that I look close the right hole looks.. modified, but I dont know..

[Dens71TA]

The switch on the right looks fishy. You can even see the pencil marks on the woodgrain for cutting the hole

Most likely you'll find some fine "hacker wiring" behind the dash because the OEM dash harness connectors only allow for ONE power door lock and ONE rear window defrost or defog switch to be plugged in.

[Formulabruce]

I wonder if the left switch has an off position? I can remember some GM cars you could not turn off the blower , only low ( looking for a reason here) I cannot power this car now its getting ready for a bead blasting

[njsteve]

The defroster was the rear window with the heat elements in it. It only had on and off positions. The defogger was the small fan sitting in the speaker mount under the package tray, which would have used a fan speed switch. Looks like someone installed both.

[The Boss]

The elusive and ultra rare dual defroster option! Bruce you found your unicorn!

Any chance somebody grabbed a junk yard switch for power locks?

[njsteve]

Are you sure it is not an ejector seat activation button? If I were you, I wouldn't sit in the passenger seat while checking to see if the switch works....

[Formulabruce]

Originally Posted by njsteve

The defroster was the rear window with the heat elements in it. It only had on and off positions. The defogger was the small fan sitting in the speaker mount under the package tray, which would have used a fan speed switch. Looks like someone installed both.

Picture.. Defog, NOt Defrost? Both switches say DEFOG Steve.... Sucks air from Behind the rear seat.....

[njsteve]

Does the rear window have heating elements? Just curious.

[Formulabruce]

Originally Posted by njsteve

Does the rear window have heating elements? Just curious.

No, and its original glass, and no 80amp alternator..
Its just a bit Odd, and I am wondering IF the blower style show does in fact shut off

[blue71ta]

I'd have to double check, but I'm pretty sure that both the rear defrost (electric grid on the glass) and the rear defogger (blower motor) say "DEFOG" on the switches.

The blower motor style says "HI" and "LOW", while the electric grid type says "ON" and "OFF".

I don't think you could order both on the same car, so I'm betting someone added the switch on the right.

[The Boss]

Here's the one from my 73 - electric grid on the glass.

[transam1972]

Originally Posted by njsteve

Are you sure it is not an ejector seat activation button? If I were you, I wouldn't sit in the passenger seat while checking to see if the switch works....

.....but then again you never joke about your work...I suppose a compressed HD front wheel spring mounted under the passenger seat with a release mechanism...an easy mod for the later T-top cars as no way I am taking a sawzall to my roof...I am still working on the gas vent/rocket launcher thru the hinged rear glass...any recommendations on what caliper machine guns for the hinged amber parking lamps?...if anyone needs a new SR electric defog. switch just PM me & pay ship

[Held for Ransom]

Switch on right looks cut in. Any wires to the doors (I wonder if they were trying to use it as a door lock switch)?

[Bentwheelbob]

Here's my set up from the Black Car. Defog on left for gridded read window, and power locks on the right. The defog switch on the 1978 is identical in construction and labeling for grids. What does your PHS show the car was equipped with originally?

[keith k]

My old '70 T/A had its original factory defogger. One switch. Picture attached.

[Formulabruce]

The PHS has just one rear defog. Thanks for the pictures. NO door holes cut. Switch seems 3 position. Was yours Keith? and did the lowest position shut it off? Thanks for all the posts..

[Held for Ransom]

Centered should be off. Down for low speed and up for higher. It will be interesting to find out what they're using the switch for.

[Formulabruce]

Thanks HFR, I will know this weekend hopefully

[rexs73gto]

Formulabruce , the rear defog switch is designed so the middle spot is the off , & all rear defog switches are made to turn off. The only blower motor that ran all the time was the heater & A/C blower that ran all the time as designed for fresh air in the car all the time. But the rear defog was off in the normal spot. Back in the day we had some guys come into the dealer to have a blower type defog put in along with the electric defog because they thought the electric one didn't work good enough so they wanted the blower ones to help get the window cleaned off faster. It was dumb but it did make the rear window clear off better.

[4birds]

The switch on the left is correct for a rear window blower. (defogger) The middle position is off , up is high speed, down is low speed. It will run as long as you want it to. The switch on the right is for the electic rear window defogger. (Really a defroster-Horizontal heating elements in the glass) These switches will have a green light at the bottom when on, and will turn itself off after a while. Both OE switches will say DEFOG. Someone obviously added the switch on the right. You could not have both from the factory. The 1970 blower type defogger is a 1 year only design. The rear package tray and back seat bulkhead are different. They redesigned the blower type defogger for the 1971 and newer Firebirds.