Heater will not work?

My heater isnt working just blowing cold air and van is smoking. I put coolant in and the heater works until the next day then doesnt work again. The needle stays in the middle.

I have a 1996 town and country with no heat on the drivers side. I ran a calibration test on the front panel and it said there was a problem with the "zone/driver actuator did not reach heat stopzone/driver actuator did not reach heat stop" I figured the actuator went bad so I got a new one, replaced it and now I get the code "blend pass. Actuator did not reach heat stop ". Is this more of a mechanical problem with the doors themselves or did I do something wrong when I installed the actuators?

To be a little more specific, when I took off the passenger actuator I noticed there was a small grey square shaft sticking out of the heater housing. When I tool off the drivers side actuator I did not see the same shaft. Is something missing, or broken as well?

And how do I check to make sure the doors are not stuck?

Thanks,
Jon B

Had heat this morning, went to store came out driving home no heat just blowing cold air. Rear defroster/rear wipers nothing lights won't even show up on rear buttons. Replaced thermostate, coolant is the right level, heater hoses warm, coolant in radiator hot car is still blowing cold air. What could be wrong?