Performed heater 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. Cleaned the exterior of the air handler and washed the outdoor coil. I did find there is no water safety switch on the secondary drain line. The indoor coil is also extremely rusted and prone to a refrigerant leak in the future. No other issues were found. The system is operational at this time.