How to solve the communication fault of frequency conversion air conditioner E6 with multimeter
What is communication fault? Power on within 15S, the inside unit can not receive the data sent by the outside unit; or during operation, the indoor unit does not receive the correct data sent by the outdoor unit for 3 consecutive minutes, then the communication fault E6 is generated.The company's inverter air conditioner adopts the communication circuit in the form of a current loop, which can be simplified and modeled according to the following diagram to understand that, by making U1 normally open, the switch of U4 can be synchronized with U3, and by making U3 normally open, the switch of U1 can be synchronized with U1. U2 synchronization. Control the switching time sequence of each optocoupler, the digital signal communication can be realized indoors and outdoors.
How to check with a multimeter? Share a few experiences:
Step 1: After powering up and turning on the power, use the multimeter AC file to test whether the external unit is powered , and whether the L-N voltage is normal? --------- If it is not energized, check the internal or external machine connection cable;
Step 2: Voltage normal for the following test
Step 3: multimeter DC file test N-COM voltage, the voltage is 0, communication power supply circuit is bad or the external controller power terminals are not plugged in, check the external electrical box of the power supply terminal connections, confirm the replacement;
Step 4: multimeter DC file test N-COM voltage, the voltage is about 3.7V fixed value, the main chip of the external machine has no output, check the electrical box of the external machine power supply wiring, load terminal connection, confirm the replacement;
Step 5: Multimeter DC file test N-COM voltage, the voltage jumps between 30V-56V, no signal feedback from the inner machine, check the connection of the main board of the inner machine, confirm the replacement;
Step 6: the above conditions are normal, change a separate COM cable, see if the internal and external machine can communicate normally, to rule out the influence of the line.
Note 1: Some faulty motherboards may have 470K resistor vulcanization or silver migration problems, resistor vulcanization, the voltage value above may produce changes.
Note 2: Under normal circumstances, the multimeter DC file to test the voltage between N-COM, the voltage will be between 5V-30V-56V regular jumps.
