Cadillac Repair: No Heat comes into the car, just cold air!, water passage, repair person

Question
Hi Bill, I have a 1993 Eldo, 4.6L engine, Touring coupe.  One day I notice I was getting no heat blown into the car to either the front or the rear seat areas.  I checked all hoses and no leaks and all hoses were very hot indicating water passage.  Still, I flushed out the system, changed the Thermostat and still no heat.  I then bought and changed the ATC module (heating control module) located next to the fire wall under the hood.  Still no heat, even with the temp. sat at 90 degrees.  The blowers all work fine, they just blow out cold are.  Can you give some others places to check.  I'm a novice repair person, but I can manage with some direction.  Thank you very much, I've enjoyed reading your responses to other questions, very enlightening.  Verne

Answer
Hi Verne, Thanks, its always nice to hear when someone enjoys reading or benefits from my posts. What you need to do is get access to the programmer by removing the glovebox and then it is straight back. It will have a 5" rod commected to an arm on top of the programmer motor. What sometimes happens is the wireing gets pulled out by the arm movement or the motor gears inside strip out. If the wires are ok then command to 60 and then to 90 several times while litely grasping the rod and see it the motor skips halfway through its travel. If so then you might be able to get just the motor from the dealer. By now parts places might have it also. Hope that helps. Bill