The heater tank is leaking.

It doesn't matter if the warm air doesn't turn on or not. Because the water has been circulating under the operation of the water pump, even if the warm air is not turned on, it will still circulate through the warm air tank and leak. If the landlord still wants to use the car, let the repairman remove the heating water pipe first, and then connect it, so that the water will not pass through the heating water tank, so there will be no water leakage, but there will be no heating, and then turn on the heating switch, just simply let the wind out.