hello everyone I'm new to the board. i have a 1996 chevy blazer s10, i just got a good deal on it but there was one problem, no heat. the guy i got the blazer from said that the when he turned on the heat it would have steam come out the vents. I also noticed that the passenger floor board was stained. so my ? is, if it's the heater core, are these common symptoms of a bad heater core. And if so, how hard are they to replace. thanks