Upon my arrival I performed a 6 month checkup on 2 heat pump systems. Flushed and treated the water removal systems, washed condenser coils using water, cleaned and treated the electrical cabinets then verified system safety and performance. I found that both systems are operating to manufacture specifications at this time. During the evaluation I noticed the American standard system has bacterial growth inside the air handler and the carrier system has some specs of bacteria starting to form. I spoke with the customer about my concerns and went over cleanings and bacterial prevention systems. On the American standard we will perform a chemical cleaning and spray the system with bio protect since it is the least used system. The carrier system we will install PCO and UV germicidal bulbs to prevent any bacterial growth in the system and we will treat the few specs of bacterial growth that are present. Customer paid 10% down today and the office will schedule our return.