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Old 08-27-2012, 12:30 PM
Charles Nix Charles Nix is offline
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Default hot air thru A/C vents

Any suggestions on where/how hot air is entering through the A/C vents when everything is shut off? My A/C works fine when it's on, but when it's off, hot air comes through the vents. I have removed the Evaporator plenum and it's sealed up tight. Anyone have any ideas on the source of the problem?
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Old 08-27-2012, 02:10 PM
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Dakota Boy Dakota Boy is offline
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You must be getting outside air coming in via the cowl vents in from of your windshield.

Up above where the passengers feet would be, there is a flapper valve (inside the duct) that can be closed to stop the outside air from getting in.
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Old 08-28-2012, 03:43 PM
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fomoco59 fomoco59 is offline
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I have that issue also. I just close the vents when not using. Maybe I'll fix that someday.

Mike Lemmon
'59 Raven Black Hardtop
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Old 09-05-2012, 03:54 PM
Charles Nix Charles Nix is offline
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Default hot air

Are you talking about the manually operated air vents on either side of the car located above the kick panels? If so, I keep them closed and still get hot air through the A/C vents. Is there another flapper valve inside the duct work not visible from the cabin? Could it be coming in through the cowl vents (where the windshield wipers are) somehow? Thanks.
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Old 09-05-2012, 04:57 PM
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DKheld DKheld is offline
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There is a valve in the evap box on the firewall and one in the passenger compartment. Maybe one of the cables from the controls on the console has broken, come loose or just out of adjustment.

I'm rebuilding mine and there is some foam on the vanes to seal them when they are closed. If you hear a metal against metal sound when you move the knobs and adjust the vanes that means the foam is gone and it won't seal very good. Unfortunately you have to take the whole thing out and apart to replace the foam seals. I'm also adding Dynamat to the inside of the Plenum to keep the heat of the engine from heating the evap box.

My goal is that when I pull up at a car show and open the door the temperature at the show will drop 5 degrees from all the cold air coming out of my car. If I can get it to snow that will be a bonus.....

Hope that helps,

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Old 09-05-2012, 06:00 PM
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simplyconnected simplyconnected is offline
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My '55 Ford had diverter-flaps like that on each side (w/heater but no A/C). They originally had inner tube-type rubber attached to seal the closure. All the rubber was GONE! I happen to have some upholstery samples, some of which were leather. They worked perfectly; supple and heavy, and rather easy to cut. Now, the flaps are very quiet and the seal is great. - Dave
My latest project:
CLICK HERE to see my custom hydraulic roller 390 FE build.

"We've got to pause and ask ourselves: How much clean air do we need?"
--Lee Iacocca
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Old 09-10-2012, 11:14 AM
Charles Nix Charles Nix is offline
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Default Hot Air

Thanks for the diagrams...........I will check out the seals and see if they are working. Sounds like a good possibility that that's the source of the problem.
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