Upon my arrival, I performed a six month check up on one heat pump system. I flushed and treated the water removal system, installed new air filter, wash the outdoor condenser coil using water, cleaned and treated the electrical cabinet with electrical insecticide then verified system safety and performance. I found the system showing signs of low refrigerant charge. I noticed that we had installed UV leak dye two years ago so I attempted a UV leak dye search and was not finding any traces. When I checked the refrigerant at the outdoor system, I could not find any traces of UV leak dye within the refrigerant. I installed leak dye back into the system in the office will need to schedule a return in about a week or two.