The machine indoor fan control circuit, as shown in the figure is in switch power pulse width to control indoor fan speed. CN - MTR first test interface {3} feet no voltage (normal DC10 ~ 28 v), so judgment is likely to be switch power failure or pulse generating circuit failure. With the oscilloscope observation IC5 {2} have a square wave signal, as shown that failure in switching power supply part. Through inspection found Q101 (C4300) has breakdown; R101 resistor (7.5 Ω / 5 w) circuit, with the same model components replacement after the commissioning, work normally.hvDservice manual download site