I own a Lennox model XC14-036-230, 14.2 SEER, 3 ton Elite condensing unit. This unit is less than a year old.

Problem: AC unit will jump start during severe lightning storms, and it emits a loud "LOW" pitched noise, which I am guessing that it's coming from the compressor

Need some help?

Note: During normal operation it emits a HIGH pitch noise.

Are you saying the unit starts by itself?

Unfortunately yes.. . The previous unit was also a Lennox and came with the house that we bought. During the 13 yrs that we owned this unit we never had problems with it during severe thunderstorms. This is a mystery to me.