HVAC Connections Behind Dash

[olds70supreme]

Sharing for others and for a question (see below). I have my dash out to refurbish and notice all the foam at the connections of the hvac duct is gone. I'm planning on running to the hardware store tomorrow to get some adhesive backed weatherstripping to use.

I also noticed that there are some large gaps in the ductwork from the main trunk to the defrost ducts (see circled area, ~ 1" gap). Is this normal or am I missing some sort of flex boot?

Last, the defrost ducts are both broken up where they attach to the bottom of the dash (see upper left arrow). The only thing I can think of is to try and epoxy them back together.

[monzaaddict]

the ducts are abs

viewtopic.php?f=1&t=43369

[1oldmf]

I had to repair/ rebuild the vents and other cheapo plastic on my el camino,
pvc cement, and some pvc plastic sheeting I had, made "L" shaped tabs, and glued them on,
along with 4 in lip on defrost duct,
patience........... goes a long way.

[olds70supreme]

Any thoughts on the center connection to the main HVAC case circled in red? There is literally a 1" gap here between the flapper door and the defrost vents. It doesn't look like anything broke off down here, but this can't possibly be the way it came from the factory, can it? When defrost is selected I have to imagine most of the air will short circuit out towards my feet instead of going to the windshield. It would be great if someone could verify this.

[Monza Harry]

Olds70supreme, the '74 Vega manual shows a sponge gasket there but it looks differently designed than your pic and my memory, the '76 manual doesn't show this part at all as it is covered in the '74 one, but it does show another sponge gasket to the A/C ducts. My car came from California so if mine is there at all, I would be shocked, as it would be the only rubber/plastic that was in decent shape on the car, steel yes that is good but the rest I saved for the last millennium. My memory shows a sponge gasket there as well, something like 3/4" thick in a med grey colour as I remember it. I hope that is useful to you. Harry

[RedFiveKBS]

Here is the detail from the parts manual.

duct1.png

duct2.png

duct.pdf

[Monza Harry]

Kevin that is the same pic I have, but his shows the duct coming into the top of the housing and the manual shows it from the rear [passenger compartment] but it does show a "Sponge" gasket there as well. his looks like my non A/C one in the yard I will try and get out there one night after work if it isn't dark, but we are busy right now so it is close for the timing on this until the weekend. Harry

[olds70supreme]

Thanks guys. Yeah, mine is definitely different from the one pictured. the airflow goes up out of the main HVAC case into the defrost ducts, not (briefly) horizontally like shown in the parts diagram.

What is the official name for the parts manual this is from? I'll have to see if I can get one for my car, that seems helpful

[Monza Harry]

That is from the "GM Service and Overhaul" manual. You list your car as a '75 Starfire, so you will need the "1974 Vega Service and Overhaul Manual" and the "1975 Starfire Service and Overhaul Supplement", and then the "1975 Fisher Body Service Manual" and of course the "1975 Oldsmobile Wiring Diagrams" That was an expensive trip to the dealer that day 30 years ago. Today you will have to scour eBay and C/L etc. for those ones you decide you need, any thing after '74 will need 4 pieces to be the complete set. These were around $20 in the "early Eighties" IIRC, expensive for a 20 year old washing dishes for $3 an hour back then almost a whole weeks pay! Harry