John Blaine, check for a few more things like :
Make sure the blower works all the time,
Check to make sure that the cooling system is full,
Check to make sure the engine heats up to operating temperature,
and make sure that all the modes on your heater operate.
If all those are satisfactory, it is posible that you have a blend door actuator problem. First try to do the calibration on the heater system. here is how "
A/C Heater Control Calibration
The A/C-heater control module must be recalibrated each time an actuator motor or the A/C-heater control is replaced. If the vehicle is so equipped, the calibration procedure also includes rear HVAC positions for each actuator motor.
Turn the ignition switch to the On position.
If equipped with the manual temperature control (MTC) system, press and hold the Rear Wipe/ Wash and Recirculation buttons for at least five seconds . If equipped with the automatic temperature control (ATC) system, simultaneously press and hold the Power and Recirculation buttons on the A/Cheater control for at least five seconds . The MTC A/C-heater control Rear Wipe/Wash button light emitting diode (LED) and Recirculation button LED, or the ATC A/C-heater control Delay and Recirculation graphics will begin to flash when the calibration procedure has begun.
The calibration procedure should take less than two minutes to complete for the manual A/C-heater control, and less than twenty seconds for the ATC A/C-heater control. When the LED's or graphics stop flashing, the calibration procedure is complete.
If the LEDs or graphics continue to flash beyond the two minute (manual) or twenty second (ATC) calibration time, it indicates that the A/Cheater control has detected a failure and a Diagnostic Trouble Code (DTC) has been set. The LED's or graphics will continue to flash even after the ignition switch is cycled Off and On, until a successful calibration is completed or until the vehicle has been driven about 8 miles."
Here is the information from a bulletin that may apply to you as well:"
GROUP: Heating & A/C
DATE: May 4, 2001
No Heat on Front Right Side
This bulletin involves replacing the blend air door shaft with a new part.
MODELS:2001 (RS) Caravan/Town & Country/Voyager 2001 (RG) Chrysler Voyager (International Markets)
NOTE : THIS BULLETIN APPLIES TO LEFT HAND DRIVE (LHD) VEHICLES WITH ZONE CONTROL OR AUTOMATIC TEMPERATURE CONTROL (ATC) HVAC SYSTEMS.
The vehicle operator may complain of no heat in any mode, from the front right side of the vehicle.
If the above condition is verified, perform the Repair Procedure.
1. Disconnect and isolate the negative battery cable.
2. Remove the silencer pad from beneath the driver side end of the instrument panel.
3. Remove the driver's side knee bolster.
4. Remove the three screws that secure the heater core shield to the left end of the HVAC distribution housing (Fig. 1).
5. Pull the heater core shield rearward far enough to disengage the two location tabs that position the front of the shield to the receptacles in the two lower finger formations of the heater/air conditioner housing near the dash.
6. Remove the heater core shield from the distribution housing.
7. Remove the two screws that secure the passenger blend door actuator to the distribution housing (Fig. 2).
NOTE : MARK LOCATION OF PLASTIC EXTERNAL STOP POSITION ON THE BLEND AIR DOOR SHAFT FOR REINSTALLATION.
8. Remove the metal blend air door shaft and plastic external stop attached to the shaft.
9. Install the new blend door shaft through the blend air door and into the housing.
10. Reinsert the plastic external stop to the blend air door shaft in the same position as it was removed. Rotate the blend air door shaft by hand to ensure the plastic door stop stops rotation of the shaft between the stop bumpers in the housing.
11. Position the blend air door actuator onto the distribution housing. It necessary, rotate the actuator slightly to align the splines on the actuator output shaft with those in the blend air door linkage.
12. Install and tighten the two screws that secure the blend door actuator to the distribution housing . Tighten screws to 2 Nm (17 in. lbs.).
13. Position the heater core shield onto the distribution housing. Be certain that the two location tabs on the front of the shield are engaged in the receptacles in the two lower finger formations of the evaporator housing near the dash panel.
14. Install and tighten the three heater core shield screws and tighten to 2 Nm (17 in. lbs.).
15. Install knee bolster.
16. Install silencer pad.
17. Reconnect battery negative cable.
18. Perform the heater-NC control calibration procedure:
a. Turn the ignition switch to the ON position.
b. Simultaneously depress and hold the Power and Recirculation buttons on the heater-A/C control for at least five seconds. The manual heater-A/C control Delay Light Emitting Diode (LED) and Recirculation LED, or the Automatic Temperature Control (ATC) heater-A/C control Delay and Recirculation graphics will begin to flash when the calibration procedure has begun.
c. The calibration procedure should take less than three minutes to complete for the manual system, and less than twenty seconds for the ATC system. When the LED's or graphics stop flashing, the calibration procedure is complete.
d. If the LED's or graphics continue to flash beyond the time stated above, it indicates that the heater-A/C control system has detected a failure and a Diagnostic Trouble Code (DTC) has been set. Use the DRBIII(R) scan tool and the appropriate diagnostic." Hope this helps, good luck.