OK, more info, none of it encouraging.

I checked the positioning pot and found it to be a single turn 8.2k one. The resistance will go to zero, briefly open, then go back to 8.2k as you turn the gear. One full revolution is exactly 0 - 8.2k. So that answers that, I don't know what the resistance should be, if anyone has access to one and can measure, that would help.

I positioned the pot to midtravel and assembled the unit with the damper gear also in midtravel.

I did the reset procedure and when the key is turned on the actuator travels to full hot and sits there. I repeated with the pot and actuator positioned on full cold and the same result was observed.

Moving the temperature selector to full cold cause no movement in the actuator.

So it isn't even continuously hunting now, it just goes to full hot. I guess my only recourse is to get a new actuator, I don't know if the EECM is a factor in all this, and if there is anything I can do in regards to testing/resetting the EECM.

 

Well, I've kept this forum in my favorites for years till I needed it. I have this same issue. All I have been doing is moving the door back and forth when the seasons changed. Just went to do it yesterday and actuator wouldn't move door off heat. So, here I am.

The actuator came out very easily. Since it was so easy, for the heck of it, I decided to epoxy the crack, because if it didn't work, it was no big deal to remove it again. Anyhow, it didn't work. May be the Harbor Freight epoxy I used, lol.

Question is, has anyone just tried to replace the gear? I've looked all over the net and so far, can't find where it's for sale.

 

I think I fixed it. At least it's working as designed now, for both air and heat.

I took advice from a link in this thread and Schrades line-up of the spindle and gear for the fix.

Prior to replacing the unit, I did some dry runs of reset process (pull RDO) and watched the mechanism work. As I watched it, it occurred to me, that since the gear was cracked, it's wasn't tight on the spindle anymore. And since it wasn't tight, the other gears were strong enough, during the reset process, to spin the broken gear on the spindle, when normally, it shouldn't be able to do that. So that's where the hot/cold condition comes from because the broken gear is going around 360 instead of riding the gear one way, then the other, to find the endpoints. The snap you would hear is when the crack made it around to the gear touching it and passed it by.

From all this data, I surmised that what I needed to do was to snug the gear back onto the spindle, to keep it from rotating on the spindle. So out came the epoxy. I lined the gear and spindle up as Schrade recommended in his post and epoxy-ed it in that position. And that was it.

The only other thing I can tell you, that I don't think others have, was that since the actuator can only go back onto the door one way, you may have to twist the door it by hand, to line it up with the spindle, so the spindle in the actuator goes back down onto the door peg.

That gear must be a cheap POS because it isn't like the resetting process takes place every time you start the vehicle. It happens in the factory once and whenever the battery is disconnected, i.e dead battery or disconnecting battery for a repair. And how often should that happen? 5 , 6, 10 times in the life of the vehicle? If you notice the pattern, most of these gear incidents happened after some repair when the battery was disconnected. Mine happened after I ran the battery dead listening to the Detroit Lions on the radio during the 0-16 season (how dumb was that?) while watching a softball game. All was well on the way to the field, after the battery jump, enter the reset process and bingo, broken gear, oscillating hot and cold.

 

Was wondering if you knew the part number for that electronic actuator? I am having the same problem.