Chrysler Repair: 2000 minivan temp control for heat, slide pots, calibration test

Question
A few weeks ago the heat in my 2000 dodge caravan quit getting hot. It was lukewarm to cold.  We replaced the thermostat. IT still ran lukewarm heat. The hoses were all getting hot, heater & both radiator hoses. so we were told it was most likely the blend door. We have since removed the dash until we could see the top of the heater box and the 3 doors were exposed.  When you turn the heat switch to defrost you can see down to a larger door which I believe is the main blend door. Is that correct? It does open when I turn the temperature switch to hot and closes when I turn to cold. Unfortunately we cannot test this because with the dash off for some reason the van will not start or even turn over. I can hear the computer making noise and see flashing codes on the instrument panel.  IS there a fail safe on the van that disables it from starting? I do not want to put the dash back together until I can figure out the heat problem because it took several hours to take it off but I am very concerned about the starting issue? SO my question is first about the blend door, is it what I am seeing or is there another blend door closer to the heater core? Second question is about the nonsatarting with the dash off?  Thanks for any help or advice.

Answer
Hi Tammy,
Did you ever try doing the calibration/cooldown self-tests of your heating/ac system? It may be that the only problem you have is that the doors are not properly "set" to match up with the temp sliders. Here is how to do it:
CALIBRATION/DIAGNOSTICS TEST ENTRY
TO INITIATE TESTS:
Set Blower motor ON HIGH
Set Mode position to Panel
Open all A/C outlets
Set Temperature to Cold (Both slide pots if equipped)
Depress WASH and REAR WIPER button simultaneously for 5 Seconds (Until all LED's light)
RESULTS:
All LED's will turn on for 5 Seconds
Calibration Test is running when REAR WIPER and INTERMITTENT are alternately flashing. Cooldown test is running if A/C and RECIRC are alternately flashing.
Acceptable results is REAR WIPER LED is the only LED flashing. Push Rear Wiper to exit.
After all tests have passed, Calibration Diagnostics and Cooldown can be run separately.
COOLDOWN TEST ENTRY
TO INITIATE TESTS:
Set Blower motor ON HIGH
Set Mode position to Panel
Open all A/C outlets
Set Temperature to Cold (Both slide pots if equipped)
Depress WASH and A/C simultaneously for 5 Seconds
NOTE: Prior to start of test, If the evaporator is already cold, the system will fail test. To correct, operate system with A/C OFF and the blower motor ON high for three minutes prior to starting test.

RESULTS:
All LED's will turn on for 5 Seconds
Cooldown Test is running when A/C and RECIRC. are alternately flashing. If A/C and RECIRC. are flashing simultaneously, Cooldown has failed

Let me know how things stand if you have the unit back together and whether you are having problems with the starter motor or with the engine not catching and running. Or does it start and then die after about 3 seconds?
Roland