My wife complained thatthe heater in her Elantra blows cold air. She says after she drives for an extended period ("a really loong time"), the air gets warm but not hot. I checked it out and the coolant was low, so I filled it. Still cold air, I replaced the thermostat, and topped off the radiator. Still cold air. The temp gage reads normally, the radiator fan works, but I don't think the coolant is circulating through the hoses (the hoses are cold while the engine is hot and the fan kicks in). At this point I suspect either the radiator is plugged, (can that happen?) or the water pump is going bad. I read something in another post about 'bleeding the system' although I have never heard of that before. Any ideas?

 

You should bleed the system. whenever coolant levels get to low it lets air in to the system.

Step 1: let the car cool
Step 2: remove the radiator cap, and fill with anti freese
Step 3: start the car with the heater on high and the radiator cap off.
Step 4: add fluid as the level in the radiator lowers. (after a few min it should stop getting lower)
Step 5: close the radiator cap and fill the overflow containor to proper lv.
Step 6: Allow car to get up to operating tempurater (when the fan comes on)
Step 7: check to see if you have heat