Super tune up performed today on a Goodman straight electric system. Heat strips are amping properly. X13 blower motor is acceptable. Evaporator coil and blower wheel are clean compressor and condenser fan motor are acceptable. Refrigerant levels were low. Could not locate a leak in the system. Checked the evaporator coil, condenser coil and as much of the line set as I could. Put in leak stop and charged the system to 10 degrees of superheat which was 16oz of 410a refrigerant. System running and cooling checked. System set back to heat at 72degrees. System operating properly at time of departure.