Heater problem, '97 Accord
 

I'm having a problem turning the heat on in my '97 North American
Accord. The cooling system, all the vent controls, blower and A/C are
working fine. I can turn the heat off with the temperature dial but I
cannot get heat on when I turn the back back to heat. To get the heat
back, I have to open the heater-core valve under the hood.

Any clues?

Tentoes