My '96 850 Turbo would only send air out the defroster, and after searching around I found this post which correctly described the problem: http://www.matthewsvolvosite.com/for...hp?f=1&t=18514 The plastic shaft had split so the flap no longer turned, and I did a simple repair similar to what is described in that post.

However, while the shaft is now repaired the motor doesn't turn when I change the dial in the car so something else is still wrong. I know the vent dial works as the fan settings change when I turn the dial to defroster, but the servo stays in the same place. I've verified that the motor itself actually works, and the position sensor pins in the motor correctly change resistance based on the position. If I manually re-position the motor and then turn the car on it will move all the way to one extreme and them not move again no matter what I try.

Has anyone had this happen before? Do I need to somehow reset the ECC so it will re-learn the correct servo positions? Would replacing the servo help since it seems to work correctly?

 

I know you do it through the OBDI port "B1" if you have it.

Self-Adjustment Of Damper Motor Limit Positions

1) Turn ignition on. Place fan (blower motor) lever in manual
mode. Turn function selector to AUT (automatic). Ensure system is in
TEST MODE 4, by pressing button on OBD I 4 times (making sure wire is plugged into socket B1)

2) When LED light stays on, enter control code 9-9-9 by pressing button on diagnostic unit 9 times in quick succession. Enter each of the 9 series 3 times, with a short pause in-between to allow LED to come on again. ECC control module is now ready to adjust damper motor limit positions automatically.

3) Wait about 10 seconds for fan to start. Turn ignition off
to exit TEST MODE 4. Turn ignition on. AC OFF and REC indicator on A/C
control panel should flash. Drive car for a few minutes at speeds
greater than 20 MPH.

4) Stop car and turn engine off, but leave ignition on for at
least 2 minutes to enable ECC control module to store all values.


LOL and I have just realised you have a 96 model car so you probably dont have the OBD I diagnostics....

 

But I do...excellent information.