At first i had a leak coming from the tube connected to the heater core...so i switched out the tube and it seems to not leak anymore but now coolant is leaking from inside my car...its come to the point where it leaked to my back seats...so my guess now is my heater core has gone bad. before i switched out the tube it was blowing heat now after replacing the tube it just blows cool air...i thought it was the thermostat but the temp on my cluster seems fine...so what do you people think?