I have a question about the prius c?

Yes. It makes the throttle response less aggressive, along with the cruise control, I think.
It also drops the cooling down a notch, taking longer to reach your desired setting.
I don't believe it affects anything else.

 

Not really. That might automatically switch the recirc ON, not off.
It switches OFF when the sensors automatically detect a need for some defrost actions.

 

@dig4dirt Normally the HVAC control allows the driver to influence the engine via heat demand. Turn it up high enough and it will burn more gas. Sounds like the eco button will curtail that and leave the driver with whatever residual heat there is.

 

Yeah that is what I have thought and experienced.
I normally dont use my heat when going to/from work at 3 miles

With my scan gauge, i know at that 125f or so is that value if/when the ice will turn on with heat turn on.
And plus i dont really get much heat unless im above 150f or so

 

Well, it actually pisses me off in my Gen3 since the other half likes to use the "auto" button
and when I start up each morning, the recirc is off.
While it doesnt matter much now that we park in the garage, it DID matter when the
humidity overnight would slip in and put moisture on the inside windshield and be a pita to get off each morn.
I have not xp it since the garage time....so fingers crossed.

In my "c" i never use that "auto" button, but have no ish with defrost control...yet it still manages to
turn off automatically at times....perhaps on the inside/outside temp thingy or timer controlled.
But it gets my ocd going and my routine is always in check to check that button light

 

No kidding it seems backwards. I thought the same thing as you and my son even laughed when I showed it to him. He was borrowing the car to drive to Ohio, figured I'd give him a Prius tip of the day. lol

But I swear to you this is the way it works. Try it for yourself. I keep my temp set to 80. I can pull up to a light (ICE already running), and it won't shut the engine off.. But if I shut ECO mode off, it'll stop immediately. Oh and in case you were wondering , the AUTO feature is not on. Which as you know will also keep your engine running to keep you warm.

My assumption for this happening is because the ECO mode is tied in with the HVAC system.