Anyway, just wanted to point out that f your vehicle is overheating due to a loss of fluid, water will not likely be passing through the heater core. This is also true if you have a block in the smaller lines servicing the heater core due to frozen coolant or a steam block.

I’m just wondering.

Seriously dude, I find these articles informative and interesting and not too long at all.

If you run the defrost fan from the beginning, it will circulate air that is gradually warming… On the other hand, if you flip on the defrost at the last minute, after the car is well preheated, HOT air will suddenly be flung at the cold windshield, thus causing (or exacerbating) cracks.

My conclusion: Preheat car with interior heat OFF, but windshield defrost ON.

The car interior is heated by using a heat exchanger, that is flowing interior air over cooling system lines. To the best of my knowledge there is a thermostat in the cooling system that prevents the coolant from circulating until a certain temperature is reached. By the time that temperature has been reached and the coolant is being used to heat the interior air, the engine should be sufficiently warmed up.

I agree with your post in principle, I think in practice it will not matter if you run the heat or not.

Thanks for your time, and correction to my understanding.

Secondly, while it is true that the heater core of any car engine can act as an auxilliary radiator (ie: by cranking the car’s interior heat you can reduce the engine’s temperature), the author may have overlooked a useful damage-saving measure.

Your car’s engine will indeed heat up faster with the car’s interior heat selected OFF. However, the potential for damage happens with the *next* step…

You get in your pre-heated car with the cool-interior-but-warm-engine, and immediately select the equivalent of “toasty interior” not to mention “defrost my frosty windshield” — All that very warm air suddenly blasts onto a very cold windshield.

Have you ever noticed how many windshields are cracked clear across the bottom, but not across the top or even the middle? — Yep, that’s from hot Defrost air hitting ice-cold glass.

*Instead*: Select Defrost (only) when you start your car. The windsheild will warm slowly enough to prevent cracking, the engine will warm up fairly efficiently, and you can crank up the interior heat after you’re on your way.

Thanks for the feedback on length. I have cut out about 100 words, just for you. It’s now 629 words and most people should be able to read that in ~2.5 minutes.

I’m sorry that you find my writing boring. Perhaps you can offer some constructive criticism on why it is boring or what would make it more interesting.