Performed heater tune-up on a Lennox heat pump system for the casita. Checked the electrical, mechanical and performance systems of the unit. Cleared, cleaned, flushed and treated the drain line and cleaned the exterior of the air handler. Secured outdoor compressor wiring and washed the outdoor coil. I did find the outdoor starter is pitted at the contacts. The homeowner was concerned about a smell in the casita. He said it seems to worsen when the a/c kicks on. I checked the ductwork and system and didn’t see any signs of rodents in the attic. I did spray some coil cleaner on the evaporator coil to see if it helps. No other issues were found. The system is operational at this time.