My 07 LTZ started blowing cold on the drivers side (I actually was thinking it wasn't blowing cold in the summer so now that's confirmed). I tried the reset a few times and nothing changed. I've heard there are a few kinds of actuators so I went in to pull it out and get the part number. While it was out I figured I might as well open her up and see if mine was dirty like the OP.
What I found was disturbing. Not sure why it got wet but it seems the actuator was submerged enough for the motor to rust pretty good. It was seized but I took all the sprockets out and churned the motor by hand until it felt better. I also cleaned the contacts like the OP did.
Figured I should reinstall and see if anything changed. I did the reset and I have heat again!!!! Feels so nice to fix this ongoing problem for free.
I'll take a photo tomorrow but once you drop the panel under the dash on the passenger side the actuator is in top of the trans tunnel. Two 7/32" bolts hold it in. Fairly easy job but fiddly.