Hello.
Have a problem with my Kenmore 90 Series model 110.67902790, and I wanted to run it by some people before I went and bought a new part.

Original symptoms: Got this dryer a few years ago and it worked fine for a while. Then one day the Auto Dry stopped advancing the timer. If we let it go it'd run forever. So for awhile we ran in Timed Dry mode and that worked fine. Then one day we ran Timed Dry and it also wouldn't advance the timer. Ran forever. Tried Air Dry as a test (had never tried it before) and it also ran forever. The clothes still get great heat and come out dry in a reasonable amount of time.

New symptoms: After reading forums for a long time I decided to look at the timer and see what was going on. I expected to see no movement in the timer motor, but when I set it to Timed Dry and flipped the panel up it was moving ok and "ticking" fine. So rather than mess with it, I left it going for 10 minutes and sure enough the timer had advanced 10 minutes. I left it for an hour or so and it had only advanced 20 more minutes. Beyond that it didn't seem to advanced much at all (though I didn't leave it overnight or anything). So I tried AutoDry to see if the symptoms had changed there too, and sure enough it advanced. This one got all the way through wrinkle guard and was a tiny tick away from Off when I came back. Problem is I had come back like 2-3 hours later and as far as I can tell my model shouldn't be doing wrinkle guard that long. I left it again and came back a few minutes later and it was still tumbling. Based on my timing and how long I stood watching it, I think it was stuck in wrinkle guard, not just on another periodic tumble. The heat had shut off correctly in wrinkle guard so at least it wasn't hot the whole time. That was late last night so I haven't tested the wrinkle guard extensively yet.

So... the only reason I can think of for the timer to suddenly behave better than it did before is maybe when I tilted the panel up something jogged loose inside it. I blew a little bit of lint/dust off it, but there wasn't much. Based on this description does it sound like a bad timer? Oh, one other symptom I forgot to mention that may shoot my timer theory out of the water: the Knit (low heat) setting gets really hot, and it seems like the other (higher heat) settings don't get hot enough. The high heat setting is almost unusable on a full load of normal clothes because it takes so long to dry them. I'm open to other theories and am no stranger to a multimeter, let me know if I need to dig into it more.

Sorry for the long post. I work in tech support and describe problems like I would want them described to me.

Sure sounds like you have a problem with the timer so I would replace that. I would also clean the moisture sensor bars that are located in the drum on the lint filter inlet grille. Dirty, gunked up sensor bars can cause problems with auto dry function. As far as the heat problem, sounds strange but temp switch power is via timer so check again after replacing timer. Timer from APP is warranted for 1 year and can be returned if it doesn't fix the problem.

Whirlpool 3976576 Timer - AppliancePartsPros.com

Eric