I have a Lennox elite series HS29-036- 1P installed 2000. Yesterday I was outside and notice the unit was making an awful buzzing sound. I went to look and the fan was not turning. I went inside and turned off the AC and then switched the breaker off. About 30 minutes later I switched everything back on and it seemed to work again. Worked fine last night and this morning same thing happened. Something is going bad, where should I look first?

My first hunch is that the fan motor has starting issues.

This can be the result of several issues, most common being a failed start capacitor on the motor, but there are other things too. Is it just the fan that isn't turning on or are both the compressor and the fan not coming on? Makes a difference on which way we go from here. A motor that doesn't start will make a loud humming noise and eventually either trip out on overload or burn up if it has power to it.

If both motors are not running, then it could be the relay that turns them on. It makes more of a chatter than a hum and would originate where the electrical connections are made on the compressor/fan assemby