GMC Repair: 97 gmc Sierra ac/heater fan control, gmc sierra, fan control

Question
I need to know about a 97 gmc Sierra 1500. The fan (low to high) control  switch has stopped working. When I bought the truck the  hi/low fan control switch worked , but the high did not. All other settings worked just fine. Now none of the settings work. IS THERE A Computer board with the fan high/ low and the cold and hot knobs with the different settings for (de-frost ,front, feet) or can I just replace the fan setting switch/knob. Please help as I can find no info abut this, and I just don't want to pay High $$$ when I think it is just this fan control knob has shorted out the switch.

Answer
Hi
First check down close to the Blower motor, follow the blower motor 2 wires up  about 8-12 inches  and there will be a connector there. That connector is VERY common for burning/melting.
If you Cannot pull the connector apart, it PROBABALLY is burned. You also MAY be able to see it brittle and just looks like it got hot.
As far as the other "settings", do they work like the mode (the air flow) and heater/air conditioner controls?
If so I would REALLY check that connector.
If not check for power to the HVAC Controller (control head) andcheck grounds.
If both OK You will either need a control head OR need to have the Blower resitstor checked..
I Really hope this helps.
Just advice from experience.
Good Luck
Pawl