I have a Carrier furnace that is controlled by a two zone motherboard. When I turn my downstairs heat on only the damper for the upstairs opens slowly until it opens all the way when the fan turns on. I put a multimeter on the open contact on the motherboard and it is sending 24volts to the upstairs damper to open about every 10 seconds until it is open all the way. I switched the damper wires for the upstairs and downstairs around on the motherboard and it does the same thing to the upstairs damper so i don't think its the damper unless both dampers are bad. What would make the dampers open when they are supposed to be closed and held close with that 1 volt rather than being sent 24volts to open? The furnace Model # is 58STA/STX and there wasn't a label for model number on the motherboard but i guess the model number is ZoneCC3ZAC01. Thanks for any help.