blend door actuator won't quit??
 

'99 S10 blazer with automatic temp controls. Son's blazer kept blowing hot air so I pulled the blend door motor behind the glove box. It looked like the board was fried in it as the gear that is always mentioned wasn't crack. Took the actuator off another blazer. It had a cracked gear. So I took the gear out of the first actuator, put in the second, and installed.
Now the actuator continually cycles back and forth, hot air then cool air. The second actuator was from a blazer with auto temp controls alsol.

Any suggestions??

Thanks

Did you run through the recalibration?

By recalibration, do you mean taking the BATT fuse out for a few minutes? I did that but it didn't help.

When recalibrating the automatic temp system by removing the RDO fuse, waiting a minute or so, replace fuse, turning ignition to on, does the door need to cycle back and forth several times to set itself?

I unplugged the actuator when it started cycling back and forth thinking it was going to fry itself. Should have let it cycle a couple minutes?

It does need to cycle back and forth a few times to learn the limits. It should not continue to do so indefinitely though.