broken vacuum hose

I hope i explain this correctly. My defroster vent is the only vent that works. I have been told this is probably because I have a broken vacuum hose. I pulled the glove compartment out and found a hose broken that is attached to a big plastic thing with other small tubes leading to the heater/ac control knobs. The hose that is broken looks like it should lead into the engine compartment. But I can't find the other end of the hose. Could someone please tell me how I can find the other end of the hose or if I should just take it to a Ford dealer. Thanks