I have a '90 Coupe with the C-68 electronic Heater/AC controls. I had no heat with an error code of 01 which is an "Air Mix Door Actuator Circuit Fault". I replaced the damper door motor as the old one was showing an internal short. The new damper door motor checks out fine; but, still no luck. I have tried a used A/C programmer and then a new A/C programmer along with a used control head. The door will move to the full cool position then move back and forth (continuous oscillation) about 1/2 inch. I have tried the reset procedure for the programmer. I have traced down the entire wiring harness to check for open circuits or shorts. The only thing that I have not tried is the removal of the wires to circuit #1995 (at C13 & C14 on the programmer and at 4 and 5 position on the control head). Circuit 1995 feeds the ALDL connector. I was not sure if the diagnostic circuit had to be intact for the AC unit to function, so I left that alone. Since the diagnostic circuit will show continuity to ground through the A/C programmer or the radio, it is not easy to test. What I need is a Star Trek engineering team to run a level 4 diagnostic....that always worked for them. So, anybody have any suggestions??? Heavy tranquilizers are in my future if I can't figure this out!!!!