Has anyone ever had this happen?

on my 1984 300D Turbo,

Usually my A/C blower operates at a speed that I'll call breezy-- not enough to really cool you on a 90 degree day, but it still beats having the windows down.

This even happens with the fan switch set to high and the temp wheel set to full cold.


but once in a great while, usually when it's cold outside, when I first start the car, the blower operates at a really high speed.

After awhile something in the climate control kicks the blower down to a slower speed. Once it does, nothing I can do can get it to go back to its previous high speed.

Is this a vacuum or an electrical problem?

Any advice will be greatly appreciated.
Thanks,

__________________
Nate Stanley
(Currently Benzless)
1985 F-250 6.9l 170K
2009 SCION XB 36.5K
2003 LS430 78K
2012 Kubota B 2320