Performed diagnostic in Lincoln. Unit is a Goodman condenser on back side of house. Unit is running and operating. Checked refrigerant levels after last tech charged system. Refrigerant levels are fine showing 128psi Lowside and 325psi Highside. Went up to attic to look at evaporator coil in furnace and all looks okay. System has incorrect sub cooling and super heat levels. System is low on refrigerant and will need to come back out to do leak search. System is leaking more refrigerant than recommended levels of leakage.