Any ideas?

Car runs fine, warms up fine, economy hasn't suffered at all.

The heater control knob won't turn all the way from cold to hot. It feels like something may have broken inside the dash.

Car is out of warranty.

Has anyone taken the dash apart on one of these?

 

Yes I've seen how the cable connects but i can't remember offhand. One of the threads has instructions for removing dash panels. You may be able to see a lot simply by removing the glove compartment. I can't remember. Maybe it will come to me later. What I do remember is there is a cable from the knob to a something that moves behind the dash. Could be the cable came loose, and end became detached, fell out the thing it fits into at the end.

 

I think this is a known defect. I have been to the dealer 3 times already for the same exact problem you are describing. Prior to last time they told me that some cable under the dash was in the way and the know was not turning as it should. Last time this happened they would not tell me anything they found. My car is getting close to the 36K end of warranty period but I now have a history of repairs for same issue so if it happens for 4th time I will go to dealer to fix for free if i still have this car. I am also going to write a detailed letter to Honda corporate telling them that I have a lemon. I had many quality control problems with this car. I think it was made on a Friday at 4:59 pm. LOL