re: A/C Help, is it the Switch or the Capacitor or both?

WPB, is your air filter clean, is your condenser coil clean and is your evaporator coil clean? These are what you can see for yourself. There are many reason why this could be happening. You're not getting 24 volts to your contactor, which means something is causing something else to trip and not send the 24 volts down line to pull in the contactor. If your compressor builds up high pressure, then it will trip a high pressure sensor, thus causing the contactor to stop pulling in. Beyond the obvious reasons stated above, you probably need to get a professional out to diagnose the issue.