My 2004 silverado crewcab battery went dead and was replaced. The Air conditioning system now only blows through the defrost vents and the dial to change the airflow does not work. Can this be reset?

check the vent control module

There is an actuator located at the bottom of the dash .. just remove it and turn that little shaft with a pair of pliers gently one direction or the other and see if that's the problem if so replace that actuator,, ((((((( be shure to unplug the actuator before starting the truck )))) and disconnect your battery when u install the new actuator .... so the climate control can relearn its position for accurate door travel...

It sounds like you have two problems. First a question though; Is your heating and air conditioning control on the dash automatic (has two knobs that rotate and a display screen in the middle), or manual (has two levers that move up and down for driver/passenger temp and a separate fan knob and mode knob).

In response to the vents being stuck on defrost and floor, from experience i can say that the most likely cause is the mode actuator has failed. If your battery has recently gone dead, that could have brought the problem to the surface. When the battery has gone dead, the heating and air conditioning controls relearn all the positions of the actuators behind the dash when the vehicle has been re-started. If there is a position sensor failing (which happens quite often) in one of the actuators, the heating and air conditioning controls won't be able to learn the correct position of the actuator and (in your case) defaults to the defrost/floor position.

The only way to fix that would be to replace the actuator. I would like to know what type of heating and air conditioning controls you have (manual or automatic) before i say anything on the blower only working on 5.

I had a similar issue on an 05 silverado. Air would only blow out of defrost vents. But this worked for me:

1) Unplug HVAC fuse for 10-30 seconds
2) Start truck
3) A/C comes out defrost - wait about 10 to 15 secs
4) A/C then starts coming out the floor vents for about 5 seconds
5) A/C then starts coming out the dash vents.
6) While the A/C is coming out the dash vents, turn A/C OFF (otherwise it cycles back to defrost for good).
7) Turn truck OFF
8) Restart truck and it should work fine

(Found solution on another forum from user "ccurran")

Sounds like it is going through the recalibration process. We run into this issue when replacing the batteries on these. In the underhood fuse block there is a HVAC fuse. Pull it, wait 30 seconds, put it back in, and turn the key to the run position. You should hear the vents moving around. wait for about a minute or so, do not touch anything. If the self test/calibration passes everything will return to normal. If after several attempts you can not get it to return to normal than there is a problem with the HVAC system that will need to be resolved.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

its a problem with the switching mechanism. you have to look up under the dash to see if you can see where the switching mechanism is. if you can not see it from there youll have to remove complete center dash

sounds like your door blend actuator which is under the dash and a pain in the **** to replace

Typically, you have a vacuum issue, air flow system is designed to FAIL in the defrost mode, so no vacuum, doors are spring loaded to blow out defrost ports.

You have a vent control actuator motor stuck,or gone out.

is clutch on a/c compressor staying engaged? most like freon leaked out and system is dry