Honda Repair: 98 Civic HX (VTEC-E) Whining Noise, civic hx, vacuum problem

Question
I'm thinking of buying a '98 Civic HX, which I believe only comes with the VTEC-E engine. IF so, I should see 35-40 mpg, since it has a Manual 5 spd transmission. The car has 126,000 miles on it, and looks to be in Excellent condition, no accidents. The only problem: An intermittent whining noise is coming from the engine compartment. It does NOT vary in pitch/frequency with a change in engine speed. It does not go away when depressing clutch, and along with the fact it doesn't vary in pitch makes me think it has nothing to do with the rotation of the engine, transmission or drivetrain. It doesn't sound as shrill as a slipping belt, if I had to guess it sounds more like a vacuum problem, or maybe some auxiliary electrical motor or pump which would not be related to engine speed. Thanks in advance!

Answer
You sure did pick a good question for my first. Noise's are tricky to diagnose to start with. But over the internet, eek. From the sound of it, this noise is happening when at idle with your head under the hood. If its not a terribly loud noise i would assume that it is a vacuum leak as you stated. If so when you rev the engine the noise should go away. Not change in pitch so much as just disappear altogether. Typically though if it is a vacuum leak it will have a fluctuating idle and possibly set a code. If it seems to be louder than what I'm imagining, I would check for a relay sticking. Turn some of the accessories on and off and see if the noise goes away. Lights, wipers, windshield sprayer, etc, etc...  If it goes away then find the appropriate relay, or motor and go from there. Hope this helps.