Help-Clarity about Heat-ONLY function

[meyek91974]

As my '90 only has heat and there is not any a/c, then would the heat only work with defrost or floor and NOT utilize the four dash-face ducts/vents?

Am I correct in my understanding of how it works?

[Team Lightning]

You are correct. No heat thru the ac vents on the dash. That's the way it was built at the factory.