I have a 2000 ACR that mysteriously lost heat ability when in the "air vent" position last year. The heater position worked fine so I did not mess with it. During a drive today, I had the selector on vent. When I turned the temp selector to heat, steam came out of only the windshield vents. It had a damp smell, but no antifreeze or mildew odor. It stopped when I turned the temp to cold. The steam on the windshield did not evaporate, even when I tried the defrost mode. I had to wipe it off with windex (makes me wonder what I just inhaled).
After the drive I smelled faint antifreeze smell but no leaks were noticeable in the engine bay.
Any idea where I need to start in fixing this? Lucky I do not live in Cali or the stuff in my lungs would cause cancer.
Let's gather more data because some of what you said in defining the problem is normal operation.
The air vent position should never blow hot, since the air box design doesn't provide for that. Heat only comes out on the floor and the defrost ducts.
During your drive today with the selector on vent, outside air should come through the dash. You cannot control the temperature in this mode. When you turned the temp to hot, anything rising from the defrost duct is only due to heat and not the blower, since it can't blow out of the dash vents and the defroster at the same time. Therefore my first guess is that this was moisture from washing, rain, etc that got hot from contact with the heater core and made steam. Then when you turned the temp to cold, you closed the air box door and it stopped.
The steam on the glass may not evaporate for a few reasons - the AC compressor isn't working, so the air is not "dry." Also that the remaining water around the heater core is still evaporating and you are blowing even more wet air on the glass.
Smelling antifreeze after the drive - inside or outside the car? If the heater core is leaking, you really should smell it inside whether the blower is on or not.
The "gasket" around the heater core ******* on top of the passenger footbox is a very pourous foam and in my case, dried and crumbled. It allowed water to seep through into the passenger side floor. I repaired this by using windshield silicone - a very runny version of silicone glue. It will run and saturate the old gasket and make it water tight again. If the connections at the water temp control valve leak, or the valve itself, it will allow antifreeze to drip right on this gasket.
All in all, I agree with Jim above and suggest that you first check the coolant level and make sure the heater core is actually full. Look at the gasket, poke it with a pencil and convince yourself it is water tight. Then run around with the heat setting on "hot" so water circulates through it. Turn the blower on "heat" and bake your feet. Drive like this (remember, driving Vipers is fun) and see if the heater core area doesn't dry out and the problem goes away or if you keep smelling the glycol.
