The technician will start the vehicle and turn on the air conditioning system, measuring the actual temperature at the vents at the lowest and highest settings with a thermometer; at the same time, they will connect a manifold pressure gauge to check if the refrigerant pressure in the high and low pressure lines is within the normal range, determining if there is a chronic refrigerant leak.

Start by asking the seller for a photo of the full vehicle registration certificate. Check that the registered owner matches the seller's company name. Any change of ownership should appear with a transfer stamp and date. Second, request a lien check. In China, vehicle mortgages are registered with the vehicle management office. A clean certificate shows no mortgage registration; if one exists, the car cannot be legally exported until the loan is settled and the lien released. Third, verify there are no unpaid traffic fines and no gaps in compulsory insurance, since these can block export clearance. Ask the platform to include a title verification step in the transaction flow, and only pay the balance after the title transfer to the export company is confirmed.

4S dealership records are directly connected to the manufacturer's database, making the data hard to tamper with and the most reliable, with original parts guaranteed; third-party repair shops usually are not connected, making their data unverifiable. Therefore, we only consider the connected records from 4S dealerships as valid historical documentation.