Anyone familiar with a vibrating/pumping sound in dash?

What is your question?

Recently purchased an 03 Cayenne S with just over 130k. Had it checked out and no leaks or problems with the cooling pipes. Also a clean CarFax. Recently hear what I thought was the cd player going out,but with further investigation, now I see it's more of a vibrating/pumping sound in the dash on the passenger side. Similar to the sound of a bad heater core but the heat works, no sweet antifreeze smells or leaks associated. This was followed the next day with check your coolant level light. I also thought it was a eide leveling but thevehicle doesnt have the option. Topped of with 50/50 P antifreeze, light went away but noise still there. Anyone else experience this? Need some help!