You must have a hole in the heater core. There is an old remedy my dad used and that was putting ground black pepper in the radiator. The pepper circulates and the water pushes it into the hole if its not too large.
To circulate coolant through the engine block, radiator and passenger compartment heater core.
The heater core has gone bad if there is coolant in the interior of the vehicle. The heater core is a small radiator that is located in the dash board. It radiates heat from the engine coolant into the interior of the vehicle.
The heater core (a small radiator for your heat) is leaking, I would suggest a new heater core as they are about as cheep to replace as they are to repair.
Given only the information provided; if the cooling system is full of coolant, lt sounds as if the thermostat is stuck in the closed position and is not opening to allow the coolant to flow into the radiator. When you run the heater in the passenger cabin, it is acting as a mini-radiator and removing the heat from the the coolant. Check/replace the thermostat.
heater core
Heater coolant bypass pipe It would be the return hose for the heater.
Drain coolant from radiator and engine block Remove passenger's side rear freeze plug and replace with block heater kit
A damaged heater core will cause coolant or water to leak onto the passenger floorboard.
drain coolant from radiator, remove one of the frost plugs in engine block, install block heater in place of frost plug, refill radiator with coolant.
well you could just turn the heater off heater blower ---- If it is a car heater then check your coolant level. the heater is driven off a heat converter that is fed by the radiator system. When the coolant fails to pump round the radiator system the car internal heater doesn't work. Driving without coolant in the system will result in the engine overheating and seizing.
It is your car's cooling system that removes the excess heat from the engine. Then, by a convection process, transfers that heat to your heater core. The heater core in your car is similar to the radiator in the front of your car; in fact it looks like a small radiator. The difference is the heater is mounted inside the car and air is blown through the fins of the core. The heater hoses transfer engine coolant to the heater core, this allows the heat from the engine coolant to be utilized and warm the passenger compartment air. The heat transferred lowers the temperature of the liquid coolant, which is then circulated back to the engine to absorb excess heat again, a continuous system. Whereas the radiator is located at your car's front grill, the unit that transfers heat to the passenger cabin ( heater core) is located inside the dashboard. Heated liquid coolant circulates through tubes in the heater core, and a heater fan blowing across those tubes, as well as through little fins encasing the tubes, directs warmth through the heating vents into your car's passenger cabin.
The heater uses the engine coolant to heat the vehicle. The radiator has a drain petcock along the bottom edge to drain the coolant system.