During the summer when it gets nice and hot outside my truck sometimes begins to make a very loud low humm...It's really loud and seems to come from my cold air intake, but its not the intake because it made that sound before I got my K&N...Does anyone know what that sound is all about?

 

IAC or Idle Air Controller. I told everyone I had a choir boy trapped under my hood for some comic relief. You can try taking it off and lubing it, I tried that but to no avail.

 

Yea i guess that makes since thanks man....but is it bad for it to make that sounds?

 

Iam thinking Fan. I put an aftermarket high flow fan blade on my 95 and when the engine warms up it makes a VERY LOUD low hum.

 

Ok yea sounds like my problem, its a very loud low hum, but i haven't put an after market fan on my truck....

 

My factory fan still hummed but the after market made it louder