Hi newsgroup. My mini van with 3.3 liter engine with 44K miles has a mild anti freeze smell occasionally. It did have the air conditioner drain blocked up for a spell-it is open now. No apparent anti-freeze leak. None on ground and no level drop over 6 weeks. No misting of the windshield. Smell only occurs before heater turned on out of the vents. With heat-no smell. Any comments on what might be causing this would be appreciated. Thanks Larry