97 jimmy problems

hello, new member here,
i just bought a 97 4wd gmc jimmy (mileage aprox 60000), i have owned it for about a month now and have brought it back 3 times for the same problem, was wondering if anybody had any thoughts or opinions.
there is a squeaking sound coming either from a belt or a pully,
the first time i brought it back, they just put some belt dressing on it and it was quiet for about a day then the sound returned. second time the changed the belt, was quiet for a few days then the noise returned, this last time , they changed the idler pully , was quiet for only a day and now noise is back, it does it at start up, and after driving for about 20 mins the noise disappears,
thank-

Hmm, I have a 97 4WD with 55,000 KM and had pretty much the same problem. The first time, the belt was changed. But then, my mechanic found the problem to be the Belt Tensioner unit (not the pulley). All has been quiet since I changed it.

Good luck.

thanks for the input-
is the the tensioner unit diffrent from the tensioner pulley?
because i had the tensioner pulley replaced as well...