I was called to a customer's home to perform maintenance on a Lennox package unit. The unit was six years old and had been having issues with the air conditioner not cooling the house. I arrived at the customer's home and performed a thorough inspection of the unit. I found that the evaporator coil was dirty and needed to be cleaned. I also found that the condenser coil was also dirty and needed to be cleaned. I cleaned the coils and replaced the air filter. After cleaning the coils, the unit started cooling the house again. The customer was very happy with the results and thanked me for my help.