Yes that is what is happening. The residue it leaves on the windshield after it evaporates is why you have to keep wiping it off. If you can't afford to fix it at this moment just disconnect the heater hoses at the firewall and connect them together with a piece of 1/2" tube and a couple of hose clamps. I limped mine through the remainder of the winter like that to avoid the repair during the cold weather. FWIW.