1. As usual, the red line is the live line, the black line is the zero line, and the other yellow line is the yellow-green line. If so, the yellow-green line is the ground line.

2. If the yellow line is not the yellow-green line, it depends on the circuit diagram of the exhaust fan. If there is no circuit diagram, use a multimeter to judge the difference.

3. When the multimeter hits the resistance 20K, measure the red and black lines first, then the black and yellow lines, and then the red and yellow lines. If there are resistance values, it proves that these three wires need to be connected with capacitors.

4. Connect the two wires with the largest resistance to the capacitor, and the remaining one is the male * * * wire. One probe is connected to the male wire, and the other probe is used to measure the two wires of the capacitor respectively. The secondary winding is a winding with high resistance, and the main winding is a winding with low resistance. There is a difference between the primary winding and the secondary winding.

5. Generally speaking, the male * * * line is connected to the neutral line, and the main winding is connected to the live line. If it is positive, it is OK. If it is reversed, it is necessary to adjust the live wire to the secondary winding. The house will naturally turn forward after the electricity is turned on.