Behind the dash. Pain in the butt to replace, one of the hardest things to do in a car from what I've been told. I've gotta get mine replaced here soon.
replace it
In the radiator, coolant recover tank, heater core, and inside the engine water jacket.
The price of the heater core is around $50. The labor costs to replace it can be as high as $300. This is a very labor intensive job.
Heater core is stopped up or thermostat is stuck open.
sell the car
nIG JOB. gET A MANUAL ON YOUR CAR AND DO THE JOB CORRECTLY.
replace your heater hoses going into and out of the heater core. One of them is probably split.
A "heater" or a "heater core"?
CHECK BLOWER MOTOR, AND HEATER CORE BOTH INSIDE THE CAR UNDER THE DASHBOARD
watch your coolant level because antifreeze is probably leaking in your heater core, another indication of leaking heater core is greasy film on inside of your windshield and it makes it hard to defrost.
You may have a stopped up heater core, or it may be a faulty heater door or heater door control. Answer: Check coolant level. Replace thermostat. Check heater control cable, located under small cover above the the passenger floorboard, near the console.
The hoses to the heater core can be disconnected under the hood. connect a water hose to the core, and try to flush the core to unclog it.