Cut off the power supply
Ensure that the air conditioning system is turned off and the power supply is cut off. This is to avoid any accident and electric shock risk.
Check the signal line connection
Check whether the signal line is connected correctly. The signal line usually consists of a control line and a power line, which connect the indoor unit and the outdoor unit respectively. Make sure that the connection is firm and there is no looseness or fracture.
Measuring resistance and connectivity
Use multimeter or signal line tester to measure the resistance and connectivity of signal line. Connect the two test probes of the instrument to the two ends of the signal line respectively, and observe the readings on the instrument. If the resistance value is close to zero or the connection state is displayed, the signal line is normal.
Check the insulation performance.
Check the insulation performance of the signal line. One test probe is connected to the metal wire of the signal wire, and the other probe is connected to the sheath of the signal wire. If the instrument shows no penetration or high resistance, the signal line has good insulation performance.
Test the transmission rate and stability.
Test the transmission rate and stability of the signal line. By turning on the air conditioning system and testing it in different modes, the transmission of signal lines between indoor unit and outdoor unit is observed. If the signal transmission is stable and the air conditioning system is running normally, it means that the signal line is working normally.