The switch valve of the truck heater leaks water.

The reasons may be inferior antifreeze, strong permeability, defective components, high pressure or overheating of the cooling system.

1. The metal pipe leaks due to corrosion, welding cracking, vibration cracking, etc., and must be replaced. 2. The rubber tube leaks due to temperature difference resistance and pulse pressure difference, and must be replaced. 3. The joint of metal tube and rubber tube leaks, so replace the clamp or reinstall it. 4. Check whether the hot air tank is damaged.