My name is julia, I have an 07 ranger. It has a lot of problems but my main concern is it blowes hot air unless i put switch to the max a/c option. so i have very hot or very cold option and nothing inbetween. basicaly if i use the knob that controls the air temputure/ air mixture nothing happens, it still blowes hot air. i replace the climate control unit-same problem. i replaced the heater control valve and that did not fix anything. please can you guys help a girl out? what else could be cousing the concern? Help