hi, are both the heater hoses getting hot?they should be both close to the same temperature around 190 -210 degrees,if they are then you need to look at the temperature door and see if the actuator is opening the door or closing the door ,the door is in the pic # XXXXX ,see if that is getting vacuum to it when you change the temp.or is moving ....guy...
also check the heater control cable
inlet heater 182 f
out let 103 f
radiator upper 180 f
radiator lower 178 f