When I first start my truck on a hot day, and turn on the A/C, the compressor makes a 'grinding' noise for about 3 seconds, and then operates normally for the rest of the day. What could that grinding noise be?

 

I would like to know to.

 

one think i tinkered with and i think worked is there is a small bolt in the middle of the compressor pulley...i tightened it while holding the pulley wheel in place with my other hand and have not heard that damn noise since...only 1 day though

 

Mine does that as well. I just let it be.

 

When i had my taurus it did something like that. It even did it when the ac was off. it turned out to be the ac clutch. Might not be the same thing but thought i would try to help.