over heating on 2003 Dodge Stratus

we replaced the thermostat thinking it was out because the car would not heat up now after replacing the heater will not blow any warm air only cold what could this be

Asked by for the 2003 Dodge Stratus
There is a Technical Service Bulletin (TSB) 24-002-04 Rev. A. to address the issues of poor A/C and Heater performance. Erratic operation of the A/C and heater systems including: Lack of cold air; Lack of hot air; Unrequested mode change - Automatic Temperature Control (ATC) only); No control of mode or temperature control; Tapping noise from blend door. REPAIR PROCEDURE: With the vehicle at room temperature 50° to 80° F., remove the Fuse #1 and Fuse #11 (M-1) circuit fuse for ten minutes to erase DTCs. 2. Install the M-1 circuit fuses and start the vehicle, this will initiate the HVAC system calibration. Allow approximately five minutes for the calibration to complete. 3. Operate the vehicle and HVAC system to verify that Symptoms and/or DTCs are gone. If tapping noise or Blend Stall/Feedback DTCs re-occur, additional diagnosis will be required. Other things to consider are; Faulty water pump, Pinched or kinked heater hoses, Improper heater hose routing, Plugged heater hoses or supply and return ports at the cooling system connections, A plugged heater core, Air locked heater core or air in cooling system.