Hi, my name is mike and I have a lennox a/c unit that won't kick on , the inside blower
Fan works but out side fan doesn't. All I hear is a click. A friend told me to replace
The capacitor first. I replaced it and have the same problem.

Try replacing the relay switch. That was always the problem when my outside unit would not run but the inside fan worked.

The click you hear means that your transformer and thermostat are working.

That click means the contactor is closing and should pass power to the outside fan motor and compressor at the same time, thus a supply power problem

This leeds me to believe that one of the contact points are burned or a burned wire @ the contactor. There could be a combination of bad fan motor and comp. but not likley

If you open any panels on A/C turn the power off FIRST!!

More information is needed as what if any sounds are heard after the "click"

Check fuses or circuit breakers for the outside unit.

The contactor can kick in meaning you have low voltage power to contactor,, but if you don`t have high voltage nothing will come on the contactor is probably fine,, check breakers and /or fuses,if OK check for 220/230 volts going in and coming out of the contactor with the contactor kicked in,, also check capicitor,, beware be careful,electricity can jar your teeth and other vital body parts