Auto Air Conditioning & Heater Repair: Heater wont adjust, gmc suburban, hi bob

Question
The heater on my 98 GMC Suburban doesn't adjust right. It blows from the vents, heater, defroster all at the same time and won't go to just the one specified on the control.

Answer
Hi Bob

One of two things is happening .  First you can try to reset your control.  If you do not have a scanner then try and disconnect your battery and reconnect to reset your control.  If that does not work then you need to check the actuator motors see if they move at all when you turn your control.  Check those things first and let me know after this it starts to get more involved.