Tech Cody Brooks arrived to customer's home. I met with Mr and Mrs Barre. They showed me inside to the thermostat and where I could get access to the attic unit. I started indoors, I opened up the cabinet and inspected the coil and blower wheel, both were clean. I looked inside the supply plenum and notice that it was very clean, and saw that they had a UV light installed. I then swapped out the filter and noticed that the return plenum had a lot of dust buildup so I brought this to the attention of the homeowner. I then headed outside to the outdoor unit, I noticed that the unit nor the home had surge protection installed. I informed the homeowners that if their unit went out due to a surge that the manufacturer would not honor the warranty. I recommended that they get a unit surge protector because they did not have any open breaker spots in there electrical panel. I then opened up the electrical cabinet to the outdoor unit, the unit was a Coleman, the board look clean and all the wi