During winter, heat worked great for both zones, one up and one down. When calling for AC now, only down zones works (compressor and fan kick on and AC flows). While the down zones works, it does pump some AC to upper floors, but not a strong air flow, so it does cool, just very slow... The up zone does not kick the compressor nor the fan on, so I changed thermostat (righttemp 8050C) and connected wires as follows, red to RC, off white to O, Blue to B, white to W, yellow to y, and green to G... the compressor nor fan will kick on when I call for AC... I have tried to short y to r, no luck... have 2 zone valves controlled by EWC panel... PLEASE HELP!! RC and RH are jumpered and I believe it is a straight AC system, as heat is oil fired forced hot air and ac unit is outside...

Did you install a jumper between RC and RH? Is this a heat pump or straight A/C system?

Straight AC... I think... oil fired forced hot air and external ac unit... and yes RC and RH are jumpered on both upstairs and down