What happened to the water in the truck heater?

If the air conditioner is turned on, the drainage of the air conditioner is blocked. If you don't turn on the air conditioner, the heater water tank will leak.

There are two reasons for heater leakage:

First, it may be that the hot water tank in the instrument panel is corroded, causing the engine coolant to leak into the cab. This is the case with your car. It is recommended to remove the instrument panel and replace the hot water tank.

Second, it may be that the evaporator drain pipe of the cold air conditioner is blocked, which leads to the opening of the cold air conditioner. There is water in the cab. It is recommended to go to the repair shop to connect the drain pipe.