Chevrolet Repair: 95 Tahoe Blower Control, resistor pack, chevy tahoe

Question
Hi!
Regarding 1995 Chevy Tahoe; well maintained with around 170k miles.
The blower (for the heater and AC) will run on high, but not on any of the lower speeds.
My Chilton manual does not have a wiring diagram for this circuitry and I can't figure it out.
I just replaced the blower itself (was squealing on start up) so I know it's not that. I removed the blower control at the dashboard and checked the control unit and I don't belive it's that either.  (I did some testing and the switch appears to be fine, plus I replaced that entire assembly a couple years ago when the temp control circiut failed.)
There's only one wire going to the blower so I assume there's some resistors or something somewhere but I don't know where to look, nor how to test.
I've found what appears to be a relay behind the glove box; it clicks and brings the blower on high.  Appears to be operating properly.  
Any suggestions?
Thanks!
-Mark

Answer
Hello Mark,
I don't work on Tahoes, but on pickups there is a resistor pack about where you are talking about behind the glove compartment. There is a connector with about six wires, and it looks like it is just bolted to the top of the heater housing. But in actuality, when unscrewed, it extends into the heater housing, which allows the airflow to keep the resistors cool.
If it isn't behind the glove compartment, look under the hood, but it will be mounted in the heater a/c assembly.

Van