Truck Repair: 1973 CHEVY BLAZER HEATER, vacuum actuators, chevy blazer

Question
MY BLAZER IS PUTTING OUT HEAT TO THE FLOOR BUT NOT THE VENTS.I ALSO HAVE ANOTHER HEATER CONTROL FOR A 1978 BLAZER BUT THIS IS DIFFERENT FROM THE 1973 HEATER CONTROL CAN I SWITCH THE CONTROLS AND RESOLVE MY PROBLEM OR IS IT SOMETHING DIFFERENT.DO YOU HAVE ANY SUGGESTIONS. I HAVE CHECKED THE DUCTS AND THEY ARE CLEAN.ALSO IF YOU HAVE ANY INFOR FOR WHERE I CAN FIND DIAGRAMS ON THEE TRUCK PLEASE LET ME KNOW THANK YOU

Answer
Hi Ray,
A 73 probably has a couple doors in the heater system controlled by little cables. They used to be notorious for the end bending, and not operating the door.
Remove the glove compartment, and you should be able to see a couple of them, and see if they are working.
As to if the other controller will work, I would just need to see them.
One of them may operate vacuum actuators.
At the public library, in the refference section, they have all the manuals, even some old ones, so make some copies of your system from a Chilton or Motors manual.
Van
Van