heater problem - i getting cold in here

[csdpb]

my heat blows cold air. if i take off the vac hose from the watercock the heat blows hot. i have changed vac hoses and made sure all are where they should be. i have flushed the system, changed the waterpump and thermostate. engine is running at normal temp.
when i pull off the vac hose from the watercock the accuator opens and heat comes on, when i put the hose on the the heat stops.
im getting cold in here so if anyone has any ideas please help