My power streering belt squeeks like crazy only when the temp drops below 40. The tentioner looks to be mounted in plan sight how tight does this thing want to be?

 

With the engine stopped of course, you can push on a belt perpendicular to it's path of rotation and it should not deflect more than a 1/4 to 1/2 inch. Tighten until you are within approximately that range. If the slipping continues, you may need a new belt. V-belts will glaze over with heat and age and will no longer grip the pulley sufficient to prevent slippage.