Squealing belt on startup - 2.7L

I have a DC Taco, 2004, 2.7L and nearly every time I start it up, the belt squeals (very loudly), it doesn't seem to matter whether the A/C is turned on or off, or if the fan is on or off....

Is there a way to tighten the belt (sorry, I'm no mechanic) or does it just have a spring tension on it?

Truck has just under 140,000 miles on it and has been very well cared for by it's original owner, and now by me...

 

k so first you have 3 belts on your truck so you need to figure which one is loose
a easy way to do this is to hit each belt with a wrench or something that can bounce off you dont want it so tight there is no movement but no loose enough for the wrench to not bounce off

ac belt has to be tightened from underneath the truck on the passenger side
alternator needs to be tightened from the alternator bracket
power steering is tightened from the top center pulley

 

I'll try to do that tomorrow afternoon and report back...

 

i put more in my first post. you have to watch out when tightening because too tight and the belt wears quicker