Tech arrived at a tune-up. It was rainy. There was a for sale sign out front. Upon inspection, the capacitor was within specs. The contactor was in working condition. The condenser coils were hosed off to assist with air flow across the coils. The Delta and refrigerant was within range. The filter was very dirty. The blower area was dirty and there was growth present. The drain was clear and bleach was poured. There was visible buildup in the lines. The customer was informed of recommendations today. He decided to move forward with adding a treatment strip to help keep the drain system clean. This item was installed today. The system was functioning upon departure.