New to the forum so any help would be much appreciated. I have an 05 GTP with manual climate control, the AC, Heat and vents work just fine as long as the temp is set all the way to hot or all the way to cold. It seems like the air temp will not change until I hit the hot or cold limit on the temp knob. For example I put the knob to the hottest setting and nice hot air will blow out of my vents, but then the air temp will not change at all until the knob is moved all the way to the coldest setting (at which point I get cold ambient air) and vice versa from cold to hot. I don’t know much about the heater core and “air blend door” but have a feeling this “door” or damper is not blending hot and cold air properly. How does this system blend the hot and cold air and what might be stopping my ability to adjust it?