This machine is the frequency conversion air conditioning earlier, has been used for seven years, insulation sleeve and cable (2.5 square centimeters copper core, four core sheathed wire) are aging. Detection signal "S" and "N" zero line side has 150 v ac voltage change, explain the internal and external communication, plating on the + 5 v, + 12 v and + 300 v dc voltage is normal, just a neighborhood this machine, just down to try it on, but boot failure, still doubt wiring insulation aging cause interference. The "S" dangling on both ends of the wire, electricity measurement between "S" and "L" has about 6 v voltage, commissioning normal after replacement of cables.Pfhservice manual download site