the bleeder valve is above the thermostat. if bleeding does not work. run the engine. there will be 2 hoses at the rear of the motor that go to the fire wall. these hoses are for the heater core. with the engine warm check if both hoses are hot. if they are both hot check the function of coolant valve to the heater core. this valve operates with a cable to the heater control. have someone adjust the heater from cold to hot, watch the valve while they do this and make sure the valve moves. remember dont open any cooling system components when hot. if the valve moves and both hoses are hot u might need a heater core. u can try running a cooling system flush through the system and install new coolant.