Most likely it's the blend door. Check heatertreater.net for a full explanation of system operation and potential failures.
low coolant
In the middle of the heater box under the dash.
The heater is controlled by the same panel as the fan switch. The temperature is controlled by a cable that moves an airflow control door inside the HVAC housing. There is no water control valve if that is what you are looking for.
2001 dodge ram 1500 ac and heater flow regulator switch does not work. works only on defrost. How to fix?
If you are asking about the blower you only have one that controls both the heater and the a/c............
In the middle of the heater box under the dashIn the middle of the heater box under the dash
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Haynes repair manual, Dodge Neon 2000 thru 2003. Book #30036
You have to remove the dash and HVAC housing.
Yes. It is in the block near the oil filter.
there is one on the 2001 3.8l its by the firewall drivers side to the left of the power steering fluid.
Your heater core has failed.