Again, stuck on with key off is going to be a resistor. A bad control board generally can't send voltage to the resistor with the key off. A bad resistor, however, can short out and send battery power to the blower at all times.

If you really want to find out, pull the resistor connector and probe the small wires with a voltmeter to ground. If you've got juice on a small wire (small purple I think) then you may have a bad head unit.

 

Can a bad resistor cause the control unit to act quirky like I listed above in regards to the fan settings?

 

Yes and no. Yes, it will make the blower speeds go stupid. No, it probably won't affect other functions unless the 2006 has a stupid bidirectional communicating resistor like some new model BMWs. (I'm fairly certain is doesn't)

Do pull it and check the wire voltages like I posted earlier, will assist in diagnosing.

 

Cool,thanks.


Edit: a guy I work with just traded his truck,which was an 06' with the AUTO climate ac. Said his was doing the same thing,he took it to gm and they replaced the resistor.


Rockauto.com has the unit for $50,so I may just roll the dice on that.