When I turn on the car air conditioner, the refrigerant pipe freezes after about 15 minutes. The compressor, condenser, pipes have been replaced, the system has been cleaned, and both the capillary filter and the evaporator filter have also been replaced. Once the refrigerant pipe freezes, the air conditioner stops working, and I have to turn it off and wait for it to defrost. When this happens, frost can be scraped off the pipe.