Sorry for that - with all buttons the compressor is not turning on - I attribute this to the system simply being out of refrigerant. With the first two buttons, I get fan and heat (as I should). With the other two buttons, I get absolutely nothing - no sounds of relays activating, no ducts moving, no heater motor activation.

If I was on Defrost or up/down, the system works normal. Go to floor or EC, and it's like the system was in OFF.