Ac power is on but unit will not come on.

How do you know you have power to the unit. Breakers on, are fuses in disonnect outside good? Does the blower inside the furnace come on? Need more info here, and we will try to help you out.

Maybe there no low voltage (smaller tstat wire {24 volt}) sending power to the contactor in condenser unit

But first have you checked with a meter,are you sure there is high voltage 230 volts at the unit

Is there any sounds whatsoever coming from the condenser unit when tstat is calling for cool or ac to be on?

Dad77 answered while I was writing my long letter, :),:)