Some time ago I posted that any time I changed the temp control from full cold on A/C, even a single click, the heat would come on full. Several explanations were offered. With the change of seasons I found the same to be true on heat. I have come to believe it may be an electronic problem since the function control often seems to point the air flow to somewhere other than where I have selected unless I cycle the **** to different positions a couple of times. On on occasion changing the function control caused a single sweep of the windshield wiper blades.

I got the blower harness recall done which did not change anything. I didn't expect it to but felt like I needed to eliminate it before troubleshooting further.

In the last few weeks and well after the recall completion, the heat problem just went away on its own. I can now control the temperature normally. Flakiness still persists on function control but is manageable.

Does this seem likely to be a failure in the control module or the wiring to the module?

 

I experienced this same exact issue yesterday immediately after changing my battery. The battery was disconnected for about 30-40 minutes in between swapping out for a new one. Not sure if the two are related, but I'll keep an eye on it.