I have a Lennox central air conditioner unit that is 6 years old. Four months ago, a technician from Dial One came out and replaced the hard start and the capacitor because the unit was not cooling the house. I also had the thermostat replaced. Now, I am having the same problem with the unit not cooling the house and now, the heat won't work. I was told by another Dial One technician that the compressor was gone out and that it was going out when the first technician replaced the parts. Is this common for a compressor to go out so soon? The outside condenser unit runs and the fan turns. Could this be something else besides the compressor?

A compressor can go bad right out of the box when new. Usually compressors last longer than 6 years but as I said before there is no real way to tell how long it will last.

I would get a second opinion on the problem before you replace the unit.