2000 Chevrolet Silverado heater wont work

Do both lines at the heater core in the engine bay feel hot (supply and return), or is it just one? Did you burp all the air out of the cooling system.

Ok, the heater core could be clogged or air locked. First try this to get the air out. When the vehicle is cooled down remove the radiator cap. Then top off coolant if needed, start the truck and turn on the heat, let it idle till it reaches normal operating temp, raise the rpm a few times to 3000 and hold for 5 seconds to help push the air out, continue to check the coolant level in the radiator to be sure it is full and to watch your gauge so it doesnt overheat. Once the upper and lower radiator hoses are hot (thermostat has opened) and you have heat at idle, place the cap back on and shut off the truck.

If the heater core is clogged then drain the coolant. Remove the heater hoses at the heater core and get a water hose and force water into return line to back flush it out. If your getting water out of the other pipe while feeding it water then you know there is no clog.