What is the exact size of the serpentine belt of Sidekick Sport 1.8l with AC

[rasmeidirt]

As the tittle says, I currently replace with 5PK1650, but during the long idle at the stop lights, I feel the belt is loosen and the belt tension-er makes noise unless I switch off the AC. Does anybody know where can I make tension a little bit or the smaller size than this one??

serp fan belts , accessory belts.  (a shop finds the true source of noise first)
ok which one?  can I guess belt 12?
#10 is the spring loaded tension-er , I say the bearing inside #10 is bad. or worse,(all bad)   the tension-er marks to show when spring is now too weak.(and arrow)
# 7 is idler pulley.
why not have shop look at it, and they use eyes and stethoscope to find the 1 part that makes noise. then bingo.
All these parts can make noise , 19,13,7,10, and 1. all have bearings all fail, sooner or later all parts fails.  if bearing feels loose it is bad.
a bearing must turn smooth only, no grinding or loose  nor wobble nor flex in any why, other than spin.
#10 is spring loaded tension-er. it the same rules but flexed up and down , and is a spring.  



most cars this old the tension-ers go bad.  , both of them and with springs inside, and all bearing related go bad.  this is what they do.

did you RTM the installer manual on this #10 device.  it must be installed correctly not just thrown on the engien.
take note of marks a,b,c,
a/b  shows the loaded tension normal window,  c= marks direction of tension.   we preload the b to a, then lay on belt and release  the center nut below.
on car we turn center bolt clockwise, with a wrench then lay on the belt and release the wrench,  if the pulley feels loose or grinds turned the bearing is bad. 

Thanks.
Number 12, the exact size??
Number 10 was replaced with Gates 38156 purchased from rockauto.com several months ago, does it go bad again?? There is something anywhere I can tighten it a bit??