i installed a new battery, now the blend door opens and closes going from hot to cold air no matter what i choose on the the dials

 

The blend door actuator goes through a learning process when power is lost and then restored, at least for the computer-controlled (set the temperature type) HVAC system. I forget the details but I do remember learning this when I had to replace my blend door actuator.

For how long does this opening and closing go on?

 

It hasn't stopped for 2 days, constantly going from hot and cold

 

Best I can suggest is investigating online how the learning is done be the blend door actuator after one is installed. On my computer-controlled one, I think it would cycle back and forth a couple times and then stop.

 

Thank you sooo much for the heads up on this. I'll give it a shot