AC Blower on before car is started

Does it have a solar sunroof option? If so, it was likely running the Solar Powered Ventilation System.

There is a lower dash switch to enable or disable it.

 

And if not, a relay might be sticking.

His response to this suggestion did not really say if you hit the bulls eye or not.

 

I saw the profile said a Three, and I couldn't remember whether the solar vent package was an option for Threes, but according to the 3G equipment thread it was available.

That's going to stay my guess. In a 2010 without the solar ventilation, there isn't any relay in the blower circuit; the 50 amp supply to the motor is powered at all times, but the motor only runs when the A/C amplifier is sending it pulses telling it to run and how fast.

So any stuck relay situation would have to be the one that powers the A/C amplifier ... but that would be the IG1 relay, so a bunch of other stuff would be on too, like the dash display.

 

I've always been curious about how helpful that feature is. Could you follow up sometime about how much cooler it makes the interior on a hot day?

 

I still have the 2010 brochure hardcopy, from my first Prius purchase, so looked it up there. But that thread has much better coverage than my brochure collection.

I'm figuring that if it had been a stuck relay, the car would most likely have been dead silent and dark with a drained 12V battery.

 

Yea probably right.
But maybe the relay only becomes "hot" when the car "wakes up".

 

Trim 3 & 4 has solar roof. I tapped into the solar lead and hooked it up to a LiFePO4 battery bypassing the 10 min turn on relay. The solar panel roof is finally useful now.

 

I don't think I can quantify it, but I genuinely like it ... I'd say it makes the interior ... "tolerable" ... where "tolerable" is not something I grew up expecting car interiors to be on hot days.

I still don't dawdle much before pushing the power button so the A/C can come on.