I was called to a home to change the air filters, clean the coils, and check the operation of the sequence. I arrived at the house and found that the air filters were very dirty, and the coils were covered in dust and debris. I used a vacuum cleaner to clean the coils and filters, and then I used a coil cleaner to clean the coils. After that, I checked the operation of the sequence and found that it was working properly. I also replaced the air filter and checked the pressure in the system.