If there is a minor leak in the lines due to bumps, it is possible that the cooling may not work upon arrival. This is a normal physical loss. The cost of vacuuming, pressure testing, and recharging refrigerant at a local auto repair shop is low and is the buyer's responsibility.

Because it's not a one-time transaction. Only by ensuring compliance checks, improving after-sales service, and providing parts can a good reputation be established, leading to repeat purchases and long-term cooperation.

We use two steps: 1. Insert a medical-grade endoscope through the spark plug hole to visually inspect cylinder wall scratches and carbon buildup on the piston top; 2. Extract an engine oil sample to check for large metal debris or emulsification (caused by coolant leakage).