2004 Winnebago Vectra 40kd
Vac pump been buzzing for a while. Here's what I know.. If I pinch the hose going to the round thing (assume it's a holding tank??) it stops buzzing. If I turn on AC it stops buzzing unless I put it on MAX AC, then it keeps buzzing. Pic attached. Should the white tube on left have a hose on it too? Do I have a leak or is pump bad?