I have a 2013 Taurus and it has developed a weird sound from somewhere behind the dash. It’s difficult to describe, sort of sound like a very quiet surging noise. It’s’ rhythmic and will do it a few times, pause and do it again. You can only hear it at low speed or idle. It happens in gear or neutral, with HVAC on or off. I replaced a blend door actuator last fall on the passenger side and it’s not a clicking sound like that. There is no way to record it, it’s too low to hear with the equipment I have. Anyone experience anything like this? TIA