Suburban rear heat valve vacuum line question

In the engine compartment, right by the heater box. There is a control valve for the rear heat with a vacuum line coming from it. 6 inches up the line it layed on the exhaust manifold and burnt and now i cant for the life of me tell where it came from. HELP. :banghead: . Thanks Eric L

Depends on whether this is a factory rear heat system or a conversion package-- but the other end should come out of some plastic conduit that leads back inside the cabin to the control for the rear air/heat-- the idea is to shut of the hot water flow to the rear heater when the rear a/c is comanded on- or the rear temp control is put on full cold......