I suspect the control panel is the issue but we need to test voltage coming into the unit to make sure everything is there. Basically the AC ECU could be the issue but it appears that only sends signal to turn on or off at different settings and does not control the display which is where your issue is.
As you can see from the wiring diagram the power supply and interface circuit is interior to the control panel.
Images (Click to enlarge)
Wednesday, December 4th, 2019 AT 8:25 AM