2001 seville

In the cold weather every time I started the car there was a "swish" "swish" sound that came from under the dash. It seems to come from the drivers side and only last a short time. The colder the outside temp was the longer the sound lasted. After making the sound for a short time it I wouln't hear it again the rest of the day. But next morning would have the swish swish sound. Anytime the outside temp was 40 or above I didn't hear the noise. Does anyone have any idea what this is? Thanks
My problem must be a wierd happening., can't get a reply.