I use recirc when the car in front of me is 20 years old and is belching noxious exhaust that I can smell. In such a situation, I don't care if it wastes gas that the AC is automatically on, its better than suffocating on gas fumes. This is unrelated to the heater, but using recirc during hot weather places less strain on the AC.Snowride said:Most car manufacturers have made the heating system turn on the a/c when defrost mode is selected. The main reason is to run the compressor once in a while. Not using it at all (compressor) during the sometimes very long winter will lead to problems when you do need it. The recirculate override in heat mode is a blessing in disguise IMHO. As already mentioned above, running recirculate in heat mode will fog all your windows up very quickly. Personally I cannot see any benifit whatsoever in using recirculate in heat mode. Yes the interior will heat up slightly faster in recirculation but what's the point if you can't see where your headed.
I'm one of those weird people who get noxious if I don't have ventilation constantly in the car.Doombringer said:If the car in front of you is spewing noxous fumes, the best bet is to turn off the entire HVAC system. I imagine that closes all outside vents and basically seals off your interior... I could be wrong. But it does disengage everything.. fans.. AC.. heater.. etc.
When you've passed the ugly exhaust fumes, kick 'er back on.