How to judge the failure of the four-way valve of the combined air conditioning unit?

The method to determine the failure of the four-way valve of the combined air conditioning unit includes the following steps:

1. The unit starts and the controller starts timing;

2. Determine the operating mode of the unit: if it is cooling mode, go to step 3; if it is heating mode, go to step 5;

3. After the unit runs for 5 minutes, the inner disk temperature Tnp of the indoor heat exchanger is obtained through the inner disk temperature sensor;

4. If Tnp ≥ 45℃ and lasts for 10 minutes, it will be judged that the four-way valve has failed, the unit will shut down and a fault will be reported; otherwise, it will be judged that the four-way valve is normal and the unit will continue to run;

5. Determine whether the unit is in defrost operation. If so, go to step 6; if not, go to step 8;

6. After running for 4 minutes, obtain the external disk temperature Twp of the outdoor heat exchanger through the external disk temperature sensor, and obtain the outdoor ambient temperature Tw through the outdoor ambient temperature sensor;

7. If Twp-Tw≤5℃, it will be judged that the four-way valve is invalid, the unit will shut down and a fault will be reported; otherwise, it will be judged that the four-way valve is normal and the unit will continue to run;

8. Obtain the outdoor ambient temperature Tw through the outdoor ambient temperature sensor; if Tw>-10℃, go to step 9; otherwise, go to step 11;

9. After running for 5 minutes, obtain the external disk temperature Twp of the outdoor heat exchanger through the external disk temperature sensor, and obtain the outdoor ambient temperature Tw through the outdoor ambient temperature sensor;

10. If Tw-Twp ≤ 0℃ and lasts for 5 minutes, the four-way valve is judged to be invalid, the unit is shut down and a fault is reported; otherwise, the four-way valve is judged to be normal and the unit continues to operate;

11. After running for 5 minutes, perform the following tests: obtain the external disk temperature Twp of the outdoor heat exchanger through the external disk temperature sensor; obtain the outdoor ambient temperature Tw through the outdoor ambient temperature sensor; obtain the unit high pressure HP through the outdoor high-pressure pressure sensor;

12. If Tw-Twp ≤ 2.5℃ and HP < 8bar and lasts for 10 minutes, the four-way valve is judged to be invalid and the unit is shut down and a fault is reported; otherwise, the four-way valve is judged to be normal and the unit continues to operate.