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Old 03-01-2013, 10:14 PM   #1 (permalink)
Cyborg ECU
California98Civic's Avatar
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,964

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,236
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Engine cooling using the heater settings

With my 80% grill blocking I keep an eye on coolant temps. I have noticed that keeping the internal fan off while setting the temp selector to hot will bring the coolant temp down, even under prolonged high-load hill climbing. But the reason I am posting is that I recently noticed that I can seemingly the same benefit if I select for the internal cabin air circulation. In that setting, with the heater fan off, no hot air comes into the cabin, but the coolant temp still drops. Anyone know why? I assume the heater is dumping the forced air somewhere else, other than the cabin, perhaps into the engine compartment itself.

The effect is that I can cool the engine, without using electricity for the radiator or cabin fans, and without forcing hot air into the cabin. On warm days, this will be a great benefit (if it works as well during the truly hot months).


See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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