I got an ATC-I system working in my old 68 NY. I had the luck the controller wasn't leaking. Main problem I had was that all the check valves that are in it all were defective and the push button control switch was leaking. There are 3 and 4 port check valves. You can simply make them yourself with aftermarket check valves together with 1 or more T-sprung. I used valves from bicycle tyres. After I replaced the push button control switch all actuators did what they should do and I re-soldered all connections in the control unit to make sure there were no bad connections.
After that I only needed to replace the thermostatic valve in the heating circuit, replace some AC hoses and the system worked fine.
If you don't need AC you can make the system working without it, with some bypasses/adjustments in the vacuum lines and a cable operated heater valve it can work. Check the vacuum circuit diagram and other info on the system and how to diagnose it at:
The technical service bulletins at
The 1970 Hamtramck Registry "1968 PLYMOUTH, CHRYSLER & IMPERIAL TSBs Index" Page
The imperial club has a lot of info on the system
(Chrysler) Imperial Automatic Temperature Control Manual
Air Condtioning Repair Information For Your (Chrysler) Imperial
And of course the original MTSC instruction movies
I used a vacuum cleaner for vacuum source and a vacuum gauge to diagnose the system. (and a multi-meter)
Good luck!