I seem to have caused a mystery. I had the fascia of the heater controls to replace the clock and it all looked good but later had occasion to use the heater while driving. All that would come out the heater vents was cold air.
Disassembled the controls again looking for something amiss but cannot seem to identify any excuse for it not working. The cable to the heater valve appears to be working as expected.
Is there some other air control doors that could be allowing only outside cold air through the system and not the heater?

Bob in Lake Havasu

Recirculator flap on fan is open (switch could have been left unplugged or wired wrong at replace fascia...) or disconnected/bad heater valve at heater box?

Thanks for the thoughts. I finally had to disconnect the heater valve as it had stuck closed while the AC was on. I got it opened by tapping it with wrench so now it works.
After a lot of work on the dash getting it checked out and put back together it was at least good to have found the issue but changing it out is saved for another day.

Bob in Lake Havasu