humming noise 2001 Ford Explorer

[W3375701]

For the last 2 years I get a humming noise coming from behind the dash board. It seems to happen "more often" when I first start up my truck and doesn't last long . It happens in both cold and warm weather. However it has happened when it has been running for awhile too. Of course when I take it to be looked at it doesn't' happen while they are working on it. The other morning when I was picking it up after getting some work done (from the day before) it started happening and I got the service tech to come out and hear the noise. He said it was the vacuum pump and he didn't even lift the hood up! He said it shouldn't hurt the engine but he would charge around 1200.00 to replace it. I have been burned in the past by mechanics and just want to be sure that is the problem. Can anyone give me some advice on what I should do. Thank you in-advance

 

[koda2000]

it might be your idle air control valve (IAC). they hum when they start wearing out and tend to make more noise when cold. Not harmful, but annoying. They're easy to replace and cost between $22-$90 depending on brand and where you purchase one. they take about 5 mins to replace. BTW, there is no vacuum pump.