GM-GMC: Air Conditioner, blower motor resistor, gmc sierra

Question
I have a 2001 GMC Sierra 1500 truck. The heater/AC blower fan speeds fan speeds 1 & 2 do not work, speeds 3, 4, & 5 work fine. Would the lower speeds not working prevent the air conditioner from working?

Answer
That is not an uncommon concern and it will not stop your a/c from working.  There is a blower motor resistor located on the passenger side right beside the blower motor. Both are coverd by a black plastic shroud that you will need to remove to access them.  The resistor simply drops the voltage of the motor to slow it down based on the desired setting from the switch.  There is only a couple of small bolts that hold it in and two connectors to unplug. Very easy to replace and not terribly expensive.
Hope this helps