Heat

make sure the coolant is full , there's 2 hoses that run into the cabin from the engine bay , see if they are both hot , do you hear the vent door open/close when you make a selection ? the fan is blowing right ? could be many things you'll have to look

No the fan is not blowing and the car is not running hot

Turn the car on and let it come up to temperature. Put the blower switch on HIGH and the heat adjuster to the HOT setting. Then open the hood and find the two hoses leading in and out of the firewall from the radiator and engine block. Both hoses should be hot to the touch and you should be able to hear the blower running from inside of the car. If both hoses are hot, you are getting good flow through the heater core. If not, then the heater core is probably blocked and needs repair. With good flow, the blower needs to be running to distribute the heated air though the cabin. If it is not, then the blower fuse, resistor (on blower motor to adjust speed settings), or blend doors are not functioning properly.