==References== a kind of squeaking inside

Hey, guys.
the following problem in the interior of my V8 when it is cold or cold. as long as the car is cold:
Under the dashboard, I type towards the passenger side, chirping it again and again. It starts, then it stops again, then it starts again, sometimes it chats for a little longer, until it eventually (depending on the cold after approx. 15-20 min. or something) quite silent, if the car was inside I would say. Or maybe even if it's all warm.
Blower runs perfectly and does not squeaky.
The sound sounds more like some air valve that's not quite tight or something? Does anyone know the sound? Where's the problem coming from? What will help? Thank you for your tips ....
LG
Steve