Quote:
Packard Don wrote:
Is your plenum the “cardboard type”? I ask because I’ll need to be doing one for factory A/C and would like to get it as nice as yours! Either that or I’ll need to find someone to duplicate it.
Don, there is no separate heater plenum with factory AC. Heat enters the AC evaporator box and depending on how a flapper door is directed by the regular heat/defroster select knob on the heater portion of the instrument panel vent control area it goes to a single defrost outlet or in full heat position, circulates freely thru the box containing the evaporator core. If the knob is positioned midway heated air will go to both.
With heated air in the box, if the dash vents are opened heat will come out just like the chilled air. Since the heater blower is not as large as the AC blower air flow is not as much as with AC. To take the place of the old heater plenum there is a slot in the box bottom and over the slot a door that opens or closes to regulate air flow. The door is operated by a push/pull knob on a shaft located at the center of the pushed out section of the box just under the glovebox. For heat you would normally opens the door and for AC you would close it but the door can be partially open so heated or chilled air can go to both the dash vents and to the floor outlet.
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