Not sure if 72 is same as 73 but wiring diagram appears same. Power for blower is provided thru pushbutton switch in any position except off. Mine was wired incorrectly ( for a non ac car) and the connector near glove box to resistor bank was left disconnected.
The blower selector switch...
3418623 (cast 8-2-71) , so I guess used in 72 vehicle, heat riser frozen but it's been sitting a while $60 plus shipping or BO
3751084 (cast 3-9-73) driver side with heat stove, $65 pus shipping or BO
3418623-1 (cast 73) -like 3418623 but used driver side on some trucks so no heat riser-cast...
3418623 (11-5-71) and 3418621 (11-29-71) heat stove included but lower sheet metal tabs broken (included) . Heat riser turns freely but spring is broken. PM me for photos- from a low mileage engine, no cracks or pitting. $125 plus shipping or BO, would trade for LD340 intake.
Edit- after...