Heater only works on low

If this has been covered I apologize I wasn't able to find it. Today my heater started to only work on the lower two settings, the higher 2 do nothing. I saw the resistor threads but they state that it will only work on hi. Is this the same situation?

 

A friend of mine has a 2007 access cab SR5 5-lug, and the HVAC system quit working altogether. It would turn on but not blow any air whatsoever. I believe it ended up being the blower motor, and I think he had it replaced when he brought his truck in for a free frame replacement. It's also possible the HVAC control itself is bad. It probably won't be cheap to buy a new one, but it is very easy for the do-it-yourselfer to remove and replace.

I removed the control while troubleshooting a problem with the A/C in my truck last spring. It was blowing ICE COLD from the driver's side vents, cool to warm from the middle-right vent, and warm humid air from the far right vent. Luckily, it turned out my truck did not have any serious problems and just needed a recharge. However, here some pics I took while I had the HVAC control removed...

 

I figured it out. Somehow the plug came partially undone from the switch. It is working now. Thank you for your help.