My outside AC fan is not spinning and just emits a continuous buzzing or humming electrical sound. I tried giving it a spin with a stick in either direction, and the fan spins easily and freely, but it still doesn't kick on. Could this be a bad capacitor, contactor, something else? The model is a Trane XE1200. Any help is appreciated. Thanks.

I’m having trouble with my AC compressor fan not starting. (a) Last summer, I noticed on one occasion that the fan had not started. I turned AC off and restarted it a little later and it took off normally. Unit seemed to operate normally after that incident. (b) This summer I noticed the same, but shutdown and restart did not work. (c) I opened the enclosure and noticed the fan had a little resistance turning. But I did not think that resistance was enough to prevent the motor from starting (I have noticed my attic fans have all developed some resistance after a few years of operation but they all seem to start normally). (d) I sprayed a little WD-40 into the fan shaft (shouldn’t have because it displaces the motor lubricant, but figured the motor was on its way to being replaced anyway) and the fan started. Once started, it seems to run normally, no unusual sounds and RPM looks normal. (e) A couple of hours later, I noticed the fan was stuck again. I could tell because I was working outside and the difference between normal operating noise and stuck fan type of noise is rather obvious. So my question is: 1. Is a faulty capacitor the main suspect here? 2. If it were a faulty cap would it start at all? Can a motor with a faulty cap start at all if there is very little friction, or is starting impossible once the cap has gone bad? P.S. The situation is a little complicated by the fact that this is happening at my parents’ house which is four hours from where I live and I typically visit only a couple of times a month. So I’d like to gather as much info as possible before my next short weekend visit (when most appliance parts stores are closed). The house has two AC units, so my parents are getting by using the second unit for now. Advice appreciated