https://bbs.wenxuecity.com/fdcj/1873948.html
Zone control board shows call signals from two thermostats. (it took us a while to realize it has that function). Zone 1 (downstairs) has air only why calling for heat. Zone 2 (upstairs work fine).
Zone 1 thermostat should send W (heat) signal, instead, it sent G and Y (cool). No time to find out why. (room temp on display is about right).
最後發現 zone 1 thermostat 有問題，換了就好了。$40 parts with scheduling function. I was worried about the zone control board. We jumped W to R and use that find root cause was thermostat instead of zone control board. I bought zone pump and will keep that as spare.
zone pump has two output (pressure and vacuum ports going to two dampers: upstairs and downstairs).
