Triumph Repair: Heater air, heater control valve, engine coolant

Question
QUESTION: I have a 79 Spitfire.  The problem I have is that even with the heater settings to cold and air circulation off I get very hot air through the heater.  I have replaced the heater control valve with no real results.  During warm summer days this becomes very uncomfortable on the legs and feet.  Anything else that you could suggest to eliminate or reduce this hot air discharge?

ANSWER: Hi Kent,
The heater control valve turns off the hot engine coolant from going through the heater core. But the coolant that is in the heater core is still hot for a short time until enough air goes through it to cool it down. You need to check to see that you adjusted the heater control valve cable correctly and that it is turned off when your control is in the off position.
Howard

---------- FOLLOW-UP ----------

QUESTION: Thanks Howard,
I made sure that the new heater control valve is all of the way in the off position, it will not go any further and visually it also looks completely off.  

It does take a while, maybe 20 or 30 minutes to really heat up to the point of being uncomfortable; is is possible that the hot engine coolant is working its way into the heater core from the other side with no control on it.  I can't figure out any other way that the hot coolant is getting in there.  If so, how would I correct that condition?

Thanks again,

Kent

Answer
No, that is very unlikely as all cars do it that way (only cut off one side) However, I have seen one keep producing heat because the coolant was low and hot steam was traveling up the one hose even though the other end was closed. Be sure the cooling system is full and turn the heat on to exhaust any air pockets, then turn it off. Also, did you check to see the valve actually turns off before you installed it? I did find a new valve that did not turn off on an MG once and it is the same manufacture that makes the valves.
Howard