I periodically notice that when I begin driving, a light breeze of warm air is being blown through the vents in the car, even though I haven't adjusted the climate controls (which are set to "fresh air" by default). If I turn on the fan for a few seconds and then turn it off, the warm air ceases.

Does anyone have an explanation of why this happens? It doesn't seem to occur all the time, just once in a while. Thanks.

 

Would your circumstances suggest this could be air that has warmed in the vent passages as the car sits in the sun? Even if it's 50 F out, sitting in the sun the air in the vent system will warm up to 80 or so, and without AC it'll only gradually cool down to the outside temperature. Any chance this is what's going on?

cheers --
doug

 

Isn't that a feature of any car?

With fresh air mode on, air small amounts of air will pass into the car to prevent stale air buildup.

 

That's possible, I suppose. Though I'm getting the impression that by turning the fan on and then off, I'm resetting the vent system to it's default setting. I'll make of point of being more aware of the outside temperature and sunlight intensity, and see if I can find some sort of pattern.

 

Maybe part of the problem is that this my HCHII is the only car I've ever owned, so I'm not completely sure how the vents are supposed to function. On that note, can anyone tell me if there is dedicated heater in the car, or is the heat always generated directly off of the engine?

 

Cabin Heat - on MOST vehicles, is generated by passing the heated engine coolant though the passenger compartment (up under the dash, near your feet, but in the center). This is often called the "heater core." Then a fan blows air through a directed blower area that encompasses the aforementioned heater core. Voila! Hot air in the cabin area.
This method is why the heater blows cold air until the vehicle warms up a little bit, because the coolant is cold too, especially on cold days (which, of course, is when you NEED a heater!).
It is this way in the Civic.