I am describing the symptom accurately, I have no idea of the cause.With the greatest of respect, I find this statement almost unbelievable....
There must be another cause of this unwanted cold air.
I pressed recirculate and demist at the same time, they flashed alternately and went through a blower test cycle. We ended up with the demister light on.
I've asked the question on another forum and "duo" valve was mentioned there too...hmmm