hey RRR, the dingus is that flapper thingy that opens (or closes) the air intake hose connected at the heat stove on cold mornings. it needs vacuum to push down that flap, then as it heats up, the flap rises back up.
Where did you learn it needs vacuum? If you are talking about the flap in the exhaust manifold, it does not require vacuum. It has a weight and bimetal spring. As the spring heats up, it allows the flap to open.
