Packard Forum Index » V-8 (1955-56)

I read on Henry's 1955 Constellation blog that he is having a heater plenum made. Does anyone know a reliable source so that I can look into have one made for my 1956 Custom Clipper's factory A/C? Is there a source for factory blueprints?

Factory AC cars did not use a plenum as such. The heater output goes directly into the AC evaporator box and is distributed in different ways.

By virtue of a flapper door heat is directed out the defroster outlet which is on the top of the box or is allowed to enter the same space as cold air would be blown. From that space the hot air can be controlled by a door on the bottom of the box or exit the AC vents. The door is controlled by a knob on the exterior.

The defroster duct is quite different from those on the non AC car. There is a single larger flattish duct which directs the defrost air from the top of evaporator box into a different opening cut into the normal defroster channel below the windshield. The non AC openings are blocked off. Duct is made of cardboard and by now most are probably very brittle and tearing apart. I don't know of a source and my original is very fragile.

When I duplicated the factory unit to upgrade to modern components I chose to make new ducts out of urethane foam for the dash runs and thin ABS sheet for the defrost.. The urethane foam is close to the originals and I tried pressing cardboard to duplicate the original defrost but was not successful in making it keep shape. Went to ABS which can be molded while warm.

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Thank you Howard! Great work that I wish I could do myself but it's not possible so I need a manufacturer that might be able to handle it and there was mention on the post that I linked that it might even be possible to obtain factory blueprints for some parts, such as the firewall cover, which I'll also need.

My shop and I are hundreds of miles apart so my time there is limited to a couple weeks at a time, several times a year so I really need to just send something off to be duplicated to have it waiting for me when I get there. Also, I generally like to make more than one while I'm at it. In the meantime, I'll save the photos you posted as I'm sure they'll come in handy.

I've not actually started working on this car yet even though I've owned it for almost half a century but I am finally getting to it on my next visit. I was up to 22 cars for many years and now am down to only six so I can give them each more attention.