I just started getting a blinking defrost light at start up that would lock out Climate controls for 15-20 seconds and then go away.

I saw a few questions here on the forums, but no answer. Well, here it is(at least for me)

I recently replaced my cabin filter and the filter wasnt seated properly. The "flap" that covers the box moves up and down depending on the recirculation selection and was obstructed. This caused the initialization error and the blinking light. Easy fix

 

Yup happened on my car too...previous owner broke the blend door by opening it up manually, it would just flap there.

I got it replaced under warranty