AC problem

[jafree]

my trailblazer 2006 is working good but i have a issue with the AC which works fine till 3 the 4th and 5th number just stops dead

what can i do to fix this

should i replace the entire AC

thanks

[bomain]

Looks like the switch (knob) is faulty, if not blower is bad.

AC is fine, dont change.