1. Failure report for repairA sign

1. Failure report for repairA sign 307 driving process, the owner of the car, idle, air conditioning switch open (A/C display bright), adjust the temperature button, air volume button and damper button, everything is normal, refrigeration effect is good. When you step on the gas pedal and then release the gas pedal, the engine cabin gives out a crack sound, and the instrument panel does not show any trouble information. The owner repeatedly tested the car, abnormal noise always exists.(1) fault checkThe first step is to reproduce the fault phenomenon and test the vehicle on the road. Open the cover of the engine room, search for the different sound source, and find that the abnormal sound source is around the compressor part. To further confirm the fault part, use a simple stethoscope to confirm that the abnormal sound part is the compressor. According to the diagnosis process of abnormal noise of air conditioning, confirm whether the transmission belt is too loose, check and find that the belt is just tight.The second step is to determine whether it is caused by clutch slip. In order to solve the customer's fault more quickly, it is agreed to disassemble the compressor and the electromagnetic clutch through communication with the customer. After disassembling, it is found that the electromagnetic clutch bearing is seriously worn. As shown in figure 4.1 and 4.2