The switches have to be set for all the ACs and heater, not just any way. Will not talk to one another. The manual I link to you shows where they have to be. When I had this issue, I change the ends on the tele cable and clean the connectors that they plug in with Electronic cleaner. If you change them watch cause they are paired color for color. Put some Die Electric compound in then once you get it all clean and working.
I have also taken apart the thermostat and clean all the switches and put new button in. Use to be able to get a kit for new button at one of the place that will rebuild them at a high price, since all they do is clean and put in new buttons. check Solder connections on board.