Having a problem in my 2008 MX-5 GT; anyone have similar problem?

It happens if it's hot out with top down or not. Almost always when it's hot I have to the top down and AC/Vent off and all the way to cool (just in case). However, the vents still seem to blow warm/hot air. It's quite annoying on a HOT summer day to have hot air blowing at you.

Anyone have this problem and know of a fix?

 

I think it's all electrically controlled (depending on your trim level), but it sounds like one vent door is simply stuck open. If you have the mechanical ***** & such to control the vents, one end of the cable could have popped off, or be otherwise disconnected.