heater box flange?

[cortcomp]

I have a 66 w/ ac and deluxe heater. The three scew square hole where the duct goes through the firewall....does anything go there like a flange or are those holes just for a heater delete plate? I cant find anything i took off that would fit, and dont see anything on the heater box side where a flange would do anything. Much appreciated.

[pimpston65]

Originally Posted by cortcomp

I have a 66 w/ ac and deluxe heater. The three scew square hole where the duct goes through the firewall....does anything go there like a flange or are those holes just for a heater delete plate? I cant find anything i took off that would fit, and dont see anything on the heater box side where a flange would do anything. Much appreciated.

there should be a flange on the underdash ac unit that joins to the outside heaterbox that you screw the 3 screws from the inside of the cab...

[pimpston65]

Originally Posted by pimpston65

there should be a flange on the underdash ac unit that joins to the outside heaterbox that you screw the 3 screws from the inside of the cab...

my mistake, i guess there isnt 3 screws. i just added ac to my K10 sub and it had thrift air and i thought the 3 screws that attached to that was gonna be the same, but it doest...

[cortcomp]

This diagram shows something might go there, but a flange wouldnt hold anything there, and no description given.

[Captainfab]

I believe that illustration is for a '60-'62 which have a larger hole in the firewall. On the '63-'66's there is no flange on the engine side of the firewall. The air duct on the inside, screws to the firewall using those 3 holes, with a foam seal. That creates the seal when the heater box outlet slides inside of the air duct. I hope that makes sense?

[cortcomp]

That does make sense, thank you. There was a good foam seal in there and it seemed to "hug" the air duct as it slid in like you mentioned. There is still some read paint there because i masked there well to keep any overspray from the new interior. (Since i do everything backwards apparently.) My evaporator seems to be leaking (could hear it when i had air pressure to it) so that box needs to drop ASAP and i have to get a new evap on the way, which works out i guess because i can have the fittings connected vs hose clamps.

I took my new seal, some very very light rtv, glued it to the outside and used 3 new screws to hold it...it is hugging the duct from the outside, and hiding the red paint, and it blends in well. Guess you live and learn, thanks for the verification!

[earl84]

I have a thrift air heater, and those three holes are for sheet metal screws to hold on a duct (heater tube?) that runs from the underhood heater core/fan assembly through the firewall and into the air routing chamber (heater box?). Sorry, I don't know the proper names for them. Don't know if the holes themselves are used for the deluxe setup, perhaps at the factory they were all just drilled and if not used, they were still there.
Can be seen really well here on post #24, http://67-72chevytrucks.com/vboard/s...hlight=heaters

[cortcomp]

That would make sense why i don't see that plate on anyone elses trucks (using the newer and deluxe heaters...Thanks guys!