Do any of you know what this part is for? It was leaking badly on my 97 Tahoe. It looks like some sort of flow valve. It's in the middle of the heater core hoses. There's one vacuum hose coming off the side that plugs into another diaphram mounted on the firewall. What would happen if I just elimate this thing? If not, what's it called so I can get a new one? I was hoping it could be a HELP part, but I doubt I'll be so lucky!