Alternator hum

My relatively new alternator (from PO; appears to be a cheap one) is making a very slight humming noise when it is under load. I can hear it with my drivers window down. The belt is new and the tension is appropriate. Checked the battery voltage and it is spot on.

Is this normal or should I be concerned the alternator will give out?

 

Sounds like the bearing is no good .

 

Would the bearing noise come and go based on the load?
Can I change out the bearing myself or do I need to get another alternator?

 

Bearing sound should be on always if it bad . Did you do a sound test on the alternator with a long screwdriver? You should be able to listen to a grinding noise .

 

The noise only happens when it is under load and will go away immediately when I turn my lights off.

 

funny, yesterday i took my bad alternator to Oriellys along with my original receipt from 2012
got new one bc of warranty

 

Was your alternator making a noise?

 

No
But instrument cluster started to flash (Subaru) diff temp/brake/battery all at same…..intermittently
When these light were on, volt meter gauge would drop