This and all the threads regarding that same thing read like a sad book!
I have performed one repair a few years back (180 degree swap) and I am currently in the middle of my second. It may be a whole new actuator, because of two areas of broken teeth, snaps falling off in my hand upon opening servo and a broken plastic axle. But, I started to wonder, what is the limit stop on/for this actuator. One poster stated that it is contained in the unit. looking at the guts I don't see how.
So, out to the car for some testing.
1) When I run it free from the redirect flapper (foam covered piece in the duct work that it is moving) it does not stop, it will just keep turning until (for too many of us) it hits a broken tooth.
2) I put a multi-meter on the plug with wires. Positive with switch in re-circ mode, negative when not (depending on lead placement). There does not seem to be a timer on the circuit (i.e. negative or positive for 20 sec then 0 volts) as experienced with test 1 and this multi-meter test.
3) Still with multi-meter attached, I moved the redirect flapper back and forth until it stopped, no voltage change, so it does not seem like there are any limit switches or position sensor in the duct work.
What am I missing here? Is the design to actually keep power this motor/servo constantly, just switching between negative and positive based on the recirc switch? All the time pushing up against the mechanics? If so, no wonder they keep breaking
Could there be a problem hidden somewhere else in the circuit that is not taking it to zero voltage when in either closed or open position?
Something in the switch?
Resistance (mechanical transformed to electrical) sensor somewhere?
Time for a cable and big lever to manually move that flapper?