Sealing up the A/C box

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axisg

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Jul 17, 2007
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I was working on the AC on the car last night and with the fan on high I noticed there was a lot of air coming back thru the heater/ AC box where the 2 tubes go in to the box ( is that the dryer ? ).

The foam used to seal up around the 2 AC tubes is 25 years old and pretty brittle. What would be the best thing to use to seal this up ? I shoved a rag in there and noticed a huge difference in the amount of air coming actually coming thru the vents.

I was thinking of using the black putty that electricians use to seal up holes when they run wires thru walls but I don;t know if it will hold up to the heat under the hood.

Any ideas ?

crappy cell phone pic below

ac.jpg
 

Longroof79

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Oct 14, 2008
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I would think you could use some 3M strip caulk.. or dum dum. Possibly even some expandable spray foam.
 
Sep 1, 2006
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Strip caulk is good stuff. If you want a big piece of foam to do the job, the stuff you want is called Closed Cell foam, NOT open cell! Closed Cell is what is used for things like the gasket where the steering column bots to the firewall, and also on vinyl tops (it's called "Landau Foam"). Closed cell does not work like a sponge and trap water while open cell is what sponges and seat upholstery is made from. Ideally, I would use a mixture of the two as the foam can seal the opening and the caulk can seal the foam to the opening.
 

billyjack

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Mar 27, 2009
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Visit your local GM Dealer. New GM cars are shipped with foam blocks stuck to the driver's door to protect the door during shipping. It's a dense black foam that doesn't absorb water. You'll often find them lying on the ground around the new car inventory. It will take some skilled trimming to do it right, but you'll have a durable solution that looks OEM. Better stuff than you could ever buy at a hardware store.
Bill
 

axisg

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Thx much.
It was a little tricky ( without wanting to take the top off the hvac box again ), but I got some of the closed cell foam in behind the tubes, then I used some of my leftover foil backed bubble ( from the floors ) to seal the rest of it up. I have about 90% of it blocked now and until the temps drop back down to something less than 90 deg F it will have to do. I spoke with my electrician buddy and he said the stuff they use to stuff the holes when drilling thru walls is good up to 200 deg F and that HVAC guys use it too so it should be good to seal up whats left of my draft. It won't rot, or shrink, so if I can find the 1/2 brick I have left then I will use that.

On a side note I got my AC topped off but the compressor is chattering and the belt is a little loose.
I bought 2 new belts
belt # 1 - is the correct size for a 1986 SS ) but because of my new heads ( Patriot Vortec ) I cannot get the compressor down far enough to get the correct size belt on. The bottom bolt on the compressor hits the lip on the valve cover

belt # 2 - is 1 size up and is just snug when the compressor is pulled back as far as it can go but is not quite tight enough

So I guess I need to find a way to get the correct belt to fit on the car. The little I did have the AC working was a dribble of cool air at best. I guess I will need to rip the dash out and seal up all the joints for the vents in the car if I relly want the air to flow.
 

mr evil

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axisg said:
I bought 2 new belts
belt # 1 - is the correct size for a 1986 SS ) but because of my new heads ( Patriot Vortec ) I cannot get the compressor down far enough to get the correct size belt on. The bottom bolt on the compressor hits the lip on the valve cover

So I guess I need to find a way to get the correct belt to fit on the car.

Would pulling a valve cover work? Assuming you have re-usable gaskets or are willing to get a new set?
 

axisg

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Jul 17, 2007
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mr evil said:
axisg said:
I bought 2 new belts
belt # 1 - is the correct size for a 1986 SS ) but because of my new heads ( Patriot Vortec ) I cannot get the compressor down far enough to get the correct size belt on. The bottom bolt on the compressor hits the lip on the valve cover

So I guess I need to find a way to get the correct belt to fit on the car.

Would pulling a valve cover work? Assuming you have re-usable gaskets or are willing to get a new set?

I ended up leaving belt #1 to roast in the sun on the shingled roof of my shed. Once it was good and hot I was able to use 2 flat blade screwdrivers to pry it on to the pullys and it's been fine since.
 

mr evil

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Where there's a will there's a way. Glad you got it on there. 8)
 
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