Just bought the Prius V yesterday, and have driven it a few times. Loving it so far. It's been between -10 C to -6 C outside (based on dashboard reading) yet every time I hit the Auto button, the A/C comes on, as pointed out in the forum. Based on the discussion, I have accepted that perhaps this is to regulate the internal humidity. I do not mind it being on - but I certainly don't want to sacrifice fuel economy when it could just simply get the cool (ok really cold) air from outside. (Perhaps external air won't change the humidity as it is attempting to do?) I think I'm not going to touch the A/C button - keep it on and let the car decide the best way to get the car to the desired temperature. Though their doesn't seem to be a consensus that this is best.
Most manuals will recommend you use the AC a minimum amount of time, all the time. During the winter, I think the AC helps when trying to defog the windows. So I just leave it as it is. The windows defog, that much quicker, The AC get's continued use, which keeps the fluid flowing...and once the windows are clear and I've been driving a while, I just turn it off. I have no real idea if that' the perfect way to approach using the AC during the winter, but it works for me.
Another consideration is that the AC system uses seals which maintain better when used periodically. While the electric compressor is less likely to leak than a conventional unit with a clutch, use will prolong the life.
Thanks The Electric Me - I changed my post before I saw your reply, because I didn't realize their were more posts after the one I had originally replied to ... what a rookie..
Just because the light is on doesn't mean the compressor is running, and in cold weather it won't unless humidity is high. If you hit the button and shut it off, it remembers that and doesn't turn it on again next trip. In spite of what gets posted around here regularly, having the A/C "on" doesn't necessarily impact MPG at all. It has a multi-speed compressor, which uses very little energy in low speed. It also shuts off when not needed. In auto mode, if the blower indicates one or 2 bars, the compressor is either off or in low speed. In low speed, I wager the compressor uses less energy than your lights do.
Back to the OP, on mine, I press the AC button so the light goes off. After that, on subsequent journeys, the AC light never comes back on again until I select it. The climate control resumes the state it was (AC light off or on) when I last turned climate off or turned the car off.
Maybe the hatchback is different, but I've the impression the A/C does not come on with Auto, unless you've expressly push the A/C button and are seeing it's lit. I figured at the time of purchase hitting Auto would trigger A/C (our previous vehicle behaved like that), but don't think so now. When A/C is on the air does have a different feel, and it'll dispel window fogging, fast.
The A/C light is just pretty much saying that it's ready if needed, but if the outside temps aren't high enough it's not coming on.
When my dealer had an open house in which we could walk through the service area and talk to the service techs, I asked one of them about this. What the service guy said is that nothing is running when the A/C light comes on. It's just showing you that the A/C is on standby and READY to come on, should you dial down the temperature to the point where you need cooling.
My C also has the ac light come on if you turn on auto. it also resets the heater so it is not on defrost. I dont like the setup. I did figure out if I use the up button on the fan control the defrost comes back on without changing settings, that way I dont have to turn the ac off and switch to defrost. So I just push the off button to save fuel and the up on the fan to bring the defrost back on. hope this helps you
Maybe then there is a difference in the logic in the various Prius iterations: on our hatchback if I push the Auto button the A/C button does not come on. And as far as I know A/C really is off, and stays off until I push the button. And I'm pretty sure A/C's not coming on, without indication. If we're driving in the rain and the windows are fogging up, it continues to be a struggle to keep them clear unless I cave and push the A/C button. Or push the front defog button. Both action dispel the humidity fast. My only quibble with our setup is that there's no "mode" choice to direct all the air to the windshield, short of pushing the front defog button, which does force on A/C. I've found short bursts of the front defog button are effective, ie: things stay defogged after, at least for a while. I find it's hells-a-popping approach too intense for longer, lol. Upon pushing the A/C button it's light stays on constantly, whether or not the A/C compressor is currently running.
