Chrysler Repair: 2000 chrysler lhs atc issue

Question
Kevin,

I have a 2000 chrysler LHS. It is not blowing heat very well at all. from time to time it will blow out some warmish air but thats it. It blows this or cold air from all vents. I ran a diagnostics self test on it and it gave me an error code #36. According to what I have read this code means that there is some communication error with the atc head. I have had people tell me that my heater core could be bad, that my blend actuator door may be bad, as well as a few other things. Winter time is coming around and I was wondering where you might recommend starting to get this problem resolved. It seems as though this is a pretty common problem. Do you know of anyone else that has had this issue and how they fixed it?

Thank you in advance,
Mark

Answer
Hi Mark,
I would focus first on the 36 code about communications failure of the ATC. There are a couple of voltage sources for the ATC and grounds as well as one wire that carries digital communication from the ATC to the body control module. So check these out:
On pin 10 of its plug there should be 12v showing on the white wire with the ignition switch in the "run" position.
On pin 12 of its plug there should be 12v showing at all times on the pink wire.
The black wires on pins 1 and 3 should show continuity to ground (any shiny chassis metal surface).
The yellow/violet wire on pin 2 should show continuity to pin 4 of the gray plug at the body control module (located under the dash at the rear side of the fuse box. It has four plugs.
If all those check out then I would go inside the ATC control and touch the connections for the socket-side of the plug pins that I listed where they attach to the ATC circuit board using the tip of a soldering pencil to be sure of good electrical solder joints on all those joints.
If all that passes then do another self-diagnosis and if 36 persists I would look for a used ATC control unit.
Sorry for the delay in responding but I just found your question in the "pool" to which Kevin had referred it.
Please read the PS (below) and respond to it.
Thanks,
Roland