**English Translation:**
Haier 3P cabinet-type air conditioner, the outdoor unit does not work, communication fault reported.
**Fault Phenomenon:** The outdoor unit does not work, and a communication fault is reported.
**Repair Process:** The service center went to the site for inspection. Both the indoor and outdoor units had normal power supply. The user's machine was a public-use device from the mobile company. The technician replaced the faulty outdoor control board with a normal one from another same-model machine. After this replacement, the Beijing Haier air conditioner repair team found that the machine returned to normal operation, thus confirming that the issue was with the outdoor control board. However, since the computer control board (part number 001A3300205) was out of stock nationwide, and the user did not agree to a discounted machine replacement, the service center decided to repair the computer board instead. The board was then sent to Gongmao for further testing. It was determined that the fault was caused by a leaking optocoupler and a leaking 5-volt capacitor, which led to abnormal operation of the external chip. After replacing the optocoupler, the 7805 voltage regulator, and the filtering capacitor, the repaired control board was reinstalled and tested. The machine functioned normally, and the fault was resolved!
**Repair Measures:** For communication faults in such machines, you can refer to the troubleshooting process used for inverter air conditioners. To resolve communication faults, first ensure that the power supply to both the indoor and outdoor units is normal. Then check if the optocoupler is functioning properly and confirm whether the communication signal lines are connected correctly.
**Beijing Haier Air Conditioner Repair Center**
August 10, 2011