Heat in Dodge Dakota

My son owns a 1999 Dodge Dakota pickup truck. Last year the heater core had to be exchanged, at the same time the AC was evacuated and recharged. Since this work was done in June, nobody turned on the heat right away. It turns out that there has been no heat in the cabin since last winter but my son -being a tough teenager- never mentioned this to me until recently. The mechanic checked the car and said that there is heat generated and that he can’t understand why there is no heat arriving in the cabin. In addition since this last check, I have realized that the AC is on all the time unless the ventilation dial is turned off.I am wondering, if these two problems are related and if something was done incorrectly when the heater core was installed. Any ideas what I can tell the mechanic when I take the car back in? How can this problem be fixed? And how can I verify that the garage made a possible mistake?

Air temperature venting in any car is either vacuum or electrically activated. It is very possible that one of the dials is not functioning properly and is, therefore, leaving the A/C on all the time. Also, when this dial is turned to different positions certain venting routes are stopped or re routed.
I strongly suggest that you take the car to a different mechanic because the one you went to previously is either too busy or doesn’t want to bother with the details involved with going through the dial circuitry to figure out what is wrong.
I know it is very hard to find an honest dealership, but this may be your only option. The dealership may have someone who is factory trained for the year of your teenager’s car. I’m semi retired from working on government fleet cars and I have learned not to trust dealerships. I have been lucky enough to find a local hole in the wall shop who happens to be the default shop when dealer mechanics are stumped. You’d be lucky to find a shop like this anywhere else in the States. I wish you luck and the advice of just keeping your eyes and ears open for a “Default” shop near you.