Stupid question but.... what is the correct position of the knobs if you want heat? Trying to trace this "no heat" problem down

The small lever on the floor by the gearshift controls the amount of heat. Pull it up to turn the heat on. The red knob on the air control panel on the dash determines the distribution of the heat. Move it to the left to send the heat to your feet, to the right to send it to the windshield and dash vents. In the middle, it splits the hot air between the two in proportion to the position.