Heater blows but no heat in my 2003 dodge ram 1500 4x4 with 4.7L engine. what can this be? its a 2003.

Does your heater motor run when you turn speed dial ? Have you checked the two hoses that run from the engine compartment to the heater core ? When car is at operating temperature, carefully touch both hoses which should be warm or hot. If only one if hot, then you may have a bad actuator. If both are hot, you may have a clogged heater core or none functioning heater motor. or resister.

If motor is not working, check fuses, if good, then check for power at the switch and then at the heater motor.

https://www.google.com/search?q=I+need+hose+route+from+heater+core+to+water+pump+and+intake+on+a+2003+Dodge+Ram+1500,+4.7+Magnum+engine.&biw=1366&bih=651&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiixOu24LXQAhVL7yYKHT6zCQYQsAQIGg

Hope this helps

either you have a bad thermostat or you have a air lock in your heater hoses remember your heater is fed by the hose by the upper rad hose return is the hose going to the water pump, to bleed the air out fill rad leave the rad cap off start engine run for 5 min. the check the coolant level,fill to top of neck replace rad cap tight, K-D tools make a special funnel to solve this air lock problem

sounds link the servo door has either broke off or is not working and it is stuck in a closed position

Take the car to Dodge automobile shop for repairs.

Not sure about your dodge, but on hondas there is a lever under the driver side vent to allow fresh(outside air) when its cold out, it will be cold, even with the heat on inside, so check to see if your has that lever somewhere on that side...hope that helps

check to see if both heater hoses are same temp when engine is at normal running temp if not heater core not flowing coolant may need to flush also make sure it does reach normal temp around 200

P0038=HO2S Heater Control Circuit High Bank 1 Sensor 2,
The oxygen sensors on your truck have an extra wire to them,they are a heated oxygen sensor,
the computer sees a problem with the heated oxygen sensor on the drivers side,before converter.
not the sensor after converter!

you might have a vacuum leak, ck the vacuum line to the firewall where the a/c lines are at and make sure a check valve is in it also.

there is a directional door actuator motor,that has gone bad.