Disconnect and cap 3/8" vacuum line from passenger intake rail and see if noise stops. That is vacuum line to front of car, which includes power brake assist (be aware before driving car). If noise is vacuum leak, will need to isolate further between HVAC mode switch or brake booster. Is also a hard plastic line running from mode switch back to heater core shut off valve that could be leaking. Bill Robertson #5939 >--- In dmcnews@xxxxxxxxxxxxxxx, Mike Substelny <msubstel@xxxx> wrote: > Paul Salsbury wrote: > > > I've acquired an odd noise!! > >