steam in cab on 1994 Mazda B3000

I have smelled antifreeze since yesterday, but no overheat. There has been no noticeable leakage, though I have refilled water. This morning I had steam coming through the vents into my cab but ther wasn't any steam coming out from under the hood out the front. Is this my radiator, heater core or ?????

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2 answers 1 comment
This is due to a leaking heater core. Get an idea as to how much this repair will cost: http://repairpal.com/estimator?car_type_id=1370
heater core needs to be replaced,do it yourself for a $25 and 1/2 hour.
how do I do it myself for $25 and 1/2 hour