I replaced my alternator yesterday along with a new Dayco Polycog belt. Before then there would be some minor squealing when the a/c was turned on but it would go away after a few seconds, now it's there until you turn the a/c off. I adjusted the belt via the adjuster down at the power steering pump but I'm thinking it may be too tight, would this cause this problem? I also went back today and cleaned the pulleys and belt since some grease had accumulated on the front of the engine over the years and most likely had made it on the pulleys and hence the belt. The a/c worked fine before this and is the same after but I noticed that when the noise starts the volt gauge drops down to just above the 8 mark which tells me the belt is slipping. Anyone got any good suggestions before I drop it off at the mechanic?

 

being to tight will not cause it to squeal,it is suppose to have about 1/4" deflection when you press on it,I would suggest tightning the belt until it stops,but not to much or you will put stress on the bearings of the alt,comp.water pump,power steering,etc.

 

I just went to start it cold and it squealed for about 5+ seconds and then stopped. It still squeals when the a/c is turned on though. This all seems to center around the a/c, which was/is operating normally through all this. I was told by someone locally that there may not be enough contact with the compressor pully and that can cause it to slip. Also, with the grooved side being somewhat porous can it absorb grease and remain slick and cause this?

 

Something else that was mentioned by the same local person was the pulley on the compressor could be worn to the point that the belt wasn't able to make proper contact, possible?

 

How does it look in comparison to the others,turning the compressor on and it squeals,the comp requires more to keep it going,so if you have a loose belt you will see it there first.

 

Does everything match up with the same number of ribs or grooves? Double check the alternator pully with ones you didn't disturb. Make sure the belt sits down in the grooves like its supposed to.

Everything has got to match and be in line.

 

I had this same problem when I changed my girlfriends water pump and alternator on her Mazda protege, her belts would pop like every 2 weeks, to fix the squeals I just changed the new pulleys with the old ones and now a year later there is nothing wrong with her car, maybe you should try it out, just a suggestion

 

Problem turned out to be the belt wasn't tight enough after all. I went by the old Haynes manual and it was nowhere near tight enough. I just started cranking down on the adjuster until it stopped slipping. I've still got to adjust it a bit further as it still slips a little when you first turn the a/c on but otherwise it's good.