Performed A/C tune-up on a Carrier heat pump system. 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. Washed the outdoor coil and verified the compressor wiring is secure. I found that the indoor coil is very rusted but is still working. All UV lights are working. No other major issues were found. The system is operational at this time.