What is the frosting of thick copper pipes in outdoor unit of Gree air conditioner?

1, refrigerant leakage, too little refrigerant, resulting in too cold oil return pipe, which will cause frost on the thick pipe. The indoor filter screen is blocked or there are too many stains in the indoor heat exchanger, which leads to poor ventilation and poor heat exchange. Micro-plugging of the system will also cause frost on the thick pipe. Improper operation, filling other types of refrigerant, of course, this situation is rare. In autumn, the temperature drops, there is a lot of rain, and frost is normal.

2. The filter screen of the indoor condenser has been cleaned, and the outdoor pipeline is not bent or crushed. When the indoor temperature is set above 26 degrees, the refrigeration is normal, and the dynamometer on the external machine tube measures five pressures. When the indoor temperature is set to 25 degrees or lower, after 20 minutes of refrigeration, the thick pipe begins to frost, and the thin pipe has dew (normal), and the compressor has not stopped (probably because the indoor temperature has never reached the preset value, but the indoor seal is good and the space is not large), and the measured pressure of the thick pipe is less than 3.5 pressures. The condenser of the indoor unit is cold, and the temperature is low when there is no normal refrigeration.