front defrost

[DanMan32]

Originally posted by Mojo40@Dec 18 2005, 03:15 AM
I'm not sure if this helps MPG much, but I noted the engine runs a lot more if climate control (and especially defrost) is on.  Truth be told, I'm just an engineer looking for any excuse to screw with all the fun controls and hack my Prius.

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You observe correctly. The system will be less tolerant of the coolant temp dropping if you demand cabin heat, and therefore will run ICE more frequently to maintain coolant temp for the benefit of your comfort.
At least for your temperature comfort. Not so comfortable if you are more focused on MPG than cabin temperature.

[galaxee]

i think afternoonnap was the first to hit it on the head. you have to have the fan on in order for the defroster to do its job.

i say, the less they do to the car the better. DH has taken it apart enough for me. of course, i do trust the work he does but i prefer it to be left well enough alone.

[Mojo40]

Originally posted by DanMan32@Dec 18 2005, 12:24 AM
You observe correctly.  The system will be less tolerant of the coolant temp dropping if you demand cabin heat, and therefore will run ICE more frequently to maintain coolant temp for the benefit of your comfort.
At least for your temperature comfort.  Not so comfortable if you are more focused on MPG than cabin temperature.

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Actually DanMan, I have forgotten to turn on Climate Control. About 10-15 minutes into the commute, I start to notice. I'm originally from northern Michigan and used to drive a 73 VW beetle, so perhaps I am used to not getting heat.

[adllewellyn]

I can't seem to get my front defrost to work at all (light comes on and all, it's just not effective) - will try the whole set-to-auto thing. I live in Texas (where it is still hot and muggy in October) and wonder if that's part of my problem... thanks.