Checked all operations in heating mode and inspected the furnace filter. Checked static pressure and found that it was passing so I took a cfm count and that passed as well too. The blower wheel wasnt dirty so I didn’t have to worry about that. I took a temperature split also. Checked all electrical components I checked evaporator coil and that looks good as well All electrical components were operating properly and the furnace fuel was burning properly as well. The customer wanted us to check their ac unit because they thought it was making a weird noise but it wasn’t. The furnace and ac unit both checked out.