Thanks to the C3VR members that helped me get this figured out. Long story, but, I had a vacuum line going from the heater control valve in the engine bay, going up to the firewall, and stopped, not connected.
I was not getting the best cooling with AC on, but it was sufficient. After the great suggestions by fellow members, I finally looked at the grommet on the firewall where the white plastic vacuum line is supposed to exit from the rear of the glove compartment. It comes from the switch there that is hooked to the temp control cable. Sliding the temp control all the way to cool when you put the AC on, causes the plunger switch behind the glove box to move. It then rations the air vacuum to the valve at the heater hose junction. Thereby, it closes off the hot water coming thru the heater box.
(Saying heater box is my interpretation, it may not be right).
I pulled the grommet out of the firewall, and the white plastic tubing was right there, hidden in the back. I pulled it out with hemostats, connected the vac line from the heater hose valve, and started it up.
Turned on the AC, and I did not put a portable temp unit at the dash vents, but it is blowing air much cooler then when this line was unhooked.
Boatman

Great news!
Glad you found it!