Okay here we go again. 1st time I want to turn on the a/c so I flip it on in the thermostat and fan starts running. I am about to leave and think to myself "I better feel the air coming out of the floor" of coarse its not cool. I walked around to see if the fan had kicked on NO Fan no noise whatsoever coming from central unit. I checked breaker its on, fan moves by hand turning. Last year I had to replace the round capacitor on the central unit and it ran fine all year. This winter my circuit board went out and my bro-inlaw who is certified in hvac replaced the board. NOw what?

Could be no power outside or could be the capasitor again. Best thing to do is push in the contactor and see if anything comes on then you will know if it is a low voltage problem or a capasitor problem.

http://www.chinacontactor.net/Products/Contactor/MBC-2X-AC-Contactor.jpg
Look to see if the button in the middle is pulled in or not. If not you can press it in with a screwdriver.

Okay so I had my wife turn on the a/c at thermostat with temp setting above what it would take to come on while I went outside to see if the contactor would do anything. I had her flip it to cool and then turn the thermostat down to where it should kick on. NOthing outside no hum no contactor activity I mean absolutely nothing. Could you give me further suggestion and/or exactly how to push in the contactor.thanks

The contactor is usually the first device that the line voltage power supply wires are connected to inside the control compartment of the outdoor unit. Use extreme caution when manually engaging, as you are dealing with 230-240 volts. Look at the low-voltage wires coming into the unit; are they spliced directly to the contactor coil leads, or does there appear to be other circuits involved (possibly in-line pressure-sensing switches)?