Dodge Repair: Heat/cool control does not work: 98 minivan

Question
Dear Roland, I searched and found one archived answer suggesting a control cable might be why the heat control slider on my 1998 Caravan does now work. However, I cannot figure if the 1998 model has a cable controlling the heater doors or if a solenoid or such is used. I don't plan to tear off the control panel until I know what I am looking to repair.

This is the situation: All was working fine, slider to the left for cooler air and to the right for hot. Now, it blows only hot air. Slider goes full left or right with no affect on the temp which stays at full hot. I would like some clue as what to do to get the heat regulator working again.  Any assistance is greatly appreciated. I am trying to nurse this old but generally trusty vehicle along for a few more miles. Being out of work makes a new car out of the question at this time.

God Bless.  Thomas.

Answer
Hi Thomas,
The temperature is controlled by one or two (if you have separate controls for passendger and driver) electrical actuators that move the "blend air door". That door directs the air to either the heater core or the a/c evaporator or a mixture of the two locations. The actuator is electrical and is driven to move by the control panel based upon the position of the lever which is essentially a variable resistor. It is all electrical in operation.
Most likely the blend door actuator is not working or the blend door is mechanically restricted from being moved by the actuator. There is self-calibration and self-diagnostic capabilities in the unit but it has lengthy description covering about 6 pages of text. The change out of the blend door actuator is done by going to the left side of the HVAC unit under the dash by removing the under-dash panel under the steering column (and the abs unit if you have anti-lock brakes). I suggest that I copy the pages that show the diagnosis/calibration and how to change the blend door actuator. and postal mail those to you. The copying would cost me about a dollar and so if you would send me back 3 postal stamps to cover that and the mailing, after you get the pages, that would be acceptable to me. So let me know your postal mailing address.
Please read the PS below and respond to it.
Thanks,
Roland