WallyP

Sometimes the small black/blue vacuum check valve near the brake booster will whine due to a leak somewhere in the HVAC vacuum system (often the comb flap vacuum actuator, powered by the orange tube).

Now THAT is a run-on sentence!

ebs

Thanks for the replies, I am getting closer to diagnosing the problem. On my console there is a switch which allows air/ventilataion to come in and also needs to be in the "on" position for the a/c to work. When I move the switch to open/close (what I assume are) the vents, the same noise appears. Do you know what the switch controls?

Thanks.