I have read some previous posts and it seems there are similar problems. My truck only has luke warm heat. I flushed the cooling system, new thermostat, OEM 195 degree, flushed heater core many times, water free flows very strong through heater core. I too have a spot on my temperature knob that sticks a little. I opened the dash, took out the temperature control panel and the cable and gears all seem to work well. Hoses to and from heater core at the firewall are hot. If it is the "door" the temp. control knob controls, how and where do I get to it? Is there a vacuum control on this vehicle also? Where? Any help would be great, thanks!