FWD not working and heater/AC blower motor problem. on 2006 Chevrolet Colorado

I have a 06 Colorado Z71 FWD. It has 100K miles. Since the truck had 80K miles the FWD has not worked. The FWD dash buttons just flash. I changed the front diff. actuator and nothing improved. Button lights will flash in all positions but nothing happens. Could this be an Encoder sensor problem or other?
My heater/AC blower motor will work all the time in high speed. All other speeds will not work sometimes. Have you an idea what’s wrong with this?

Asked by for the 2006 Chevrolet Colorado
Good chance encoder motor has failed. Best take it to shop that has scanner that can run self diagnostics on
4X4 system. That system is not to hard to diag. Better than thowing parts at it. The A/c system is likey a blower module problem...but there again best be tested before thowing that part at it either.
Thank you. This is helpful. Where is the encoder motor located?
Where is the Blower module located?
1 more answer
My truck will sometimes turn off at the stop signs it been doing that for a few months. Then today I whent to the store and it ran good the getting ready to leave it it won't start. I put some starter fluid and it started to run rough and it won't stay on