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Need help with A/C Heat

6

69Crazy

Guest
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!!!!

Thanks,
Louie
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Any chance that the temp sendor is telling the control head that you are already hot and it is closing off the heat?
 
6

69Crazy

Guest
Worth a look

It could possibly be the internal temp sensor giving some erratic feedback to the programmer.....worth taking a look. I just tested it for open circuit as per the manual...better to test it for resistance through a variety of temperatures. I think that I will do the same for the Sun Load Sensor and the Outside Temp sensor (if I can find the dang thing).

Louie
 
6

69Crazy

Guest
In case you were wondering

Thanks again to 69MyWay...he usually has the answer or at least a good direction to take....plus he talked me out of arson!!!!

The problem was the wiring harness....hard to detect, but if you hang in there it can be found.

This problem was related to a previous repair attempt! Go bravely forward and do your own work....nobody cares as much as you do.

Louie
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
As much as I would love to see that 69 of yours sporting 1990 technology, I am much happier you are staying the course.

We had a bad wire in our 90 that was blowing the back up light/blinker fuse. I chased it for months. I even put a circuit breaker in the fuse panel at one point so at least it would have blinkers again after it cooled down. Finally, I hardwired the blinkers and left the back up light dead.

While I had the engine out I traced the harness and found a bad spot that would wiggle/jiggle, then short the wire out.

Crazy stuff!
 

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