Found that the outdoor unit was not running and indoor unit fan was operating when I arrived. Brandon informed me that the indoor unit was not running before he reset indoor and outdoor units. Checked outdoor unit trouble codes and found a low superheat lockout which is typically caused by low airflow conditions. Indoor unit utilizes a frequency drive which is very sensitive to "dirty" energy. Brown out may have caused indoor unit fan to stop operating, which would then cause outdoor unit low superheat lockout. Reset lockout and saw system begin operating correctly. Verified blower belts are tight and return air filters are clean. I will speak with the office to determine if any further action is required.