On October 13, 2021 I arrive to a previous customer now member upon arrival agree to the customer and she stated that the furnace was making a banging sound so I started the system to see if I could hear it I didn’t hear anything to begin with so I completely disassembled the furnace put the blower out with the board off found a weak capacitor let the customer know that the capacitor is weak that that could be the issue and then I reassembled everything and had the system running when I disconnected the pressure switch from the system the blower went from high-speed to Low speed you could hear it jarring but it was not anything that was major when I put the pressure switch back into play you could hear switch from low-speed to high-speed same thing just a slight thump you could barely hear explain to the customer that they have a multi stage furnace and that’s the blower switching from low-speed the high speed with the gas valve everything‘s working properly at this time thank yo