Shut the A/C off?

[larryenok]

Lemme guess, your friend doesn't own a Prius - Right?

[pjconner]

That sounds old school. I remember when people used to shut off the a/c, radio and everthing else before shutting down a car. Rediculous if you ask me.

[Walker1]

Originally posted by larryenok@Mar 4 2006, 11:35 PM
Lemme guess, your friend doesn't own a Prius - Right? 

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Actually, she does own a Prius. The problem is I think she read it in the owner's manual. You can't believe everything you read. This forum shows us items that the engineers missed on.

In any event, I don't like to shut the A/C off every time I shut the car down.

[aaf709]

Originally posted by Walker1@Mar 6 2006, 09:03 AM
Actually, she does own a Prius. The problem is I think she read it in the owner's manual.

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Could you ask her what page it is in the manual? That way we could look at it and see why she interpreted it that way.

[Charles Suitt]

"I was told by a friend..." **SIGH**
... and a Prius owner to boot.

The upside: Most Prius pilots are well-versed in the features, capabilities and caveats regarding their Prii, however, we still have some who still just "don't get it."

Technically, she's right... Without a doubt, use of the cooling capability of the "Air Conditioner" will consume energy which does have to be replaced, ultimately from gasolene (the ONLY source of energy in the Prius). Use for heating would also have a marginal effect since in cold weather the ICE would run enough to keep the cooling fluid warm. In any case, the overall effect would be so small as to be unimportant.

[jeromep]

I basically think that Ron Popiel is a brilliant salesman and entrepreneur, so I'll quote him, "set it and forget it." In READY with the mode selector in P, R, D and B the vehicle is always able to maintain both 12v and HV battery levels inside the given computer parameters. No possibility of draining the HV or 12v system in a normal operating mode. If the vehicle is in N the vehicle cannot use the ICE to charge the HV battery. It is in this mode that it is remotely possible for an operator to drain down the HV battery, but not to a damaging level, but to the bottom threshold of the vehicle’s SOC tolerance and then the vehicle will just shut itself off to protect the HV battery.

Now if you leave a dome lamp on, a door ajar, the hatch open and loose you expose the 12v battery to drainage because lights are on which consume battery power. Those of us who have had the car long enough and have done enough “experimentation” have learned that the vehicle will only run in ACC mode for 1 hour and then the vehicle will turn off (learned this at a drive in theatre where stereo movie sound is piped in through car radios, really cool).

The car has many protections on the HV battery system that prevent any damaging drain on the HV battery. The 12v aux battery has nearly no protection against stupid operator syndrome. That is why we should all strive to be smart operators.

Since the A/C system is electric, the compressor is not connected to the belt drive system on the ICE. This means that the A/C system is not robbing power from the ICE, but is rather taking its energy from the HV electrical system. The compressor is also variable speed, so it only uses the electrical power necessary to maintain cabin temp at your setpoint. The closer the A/C system gets to your setpoint, the slower the compressor runs. This reduces the amount of power necessary to attain and maintain cabin temperature. The A/C compressor does use energy which has to come from someplace. That is going to be gas power that is then turned into electrical power while driving, or it could also be power gained from regenerative braking. However, vehicle driving performance is not reduced by having the A/C compressor running, unlike nearly all other vehicles with belt driven A/C.

Using your A/C system is essential. A long time I learned ago from a soft-spoken service department manager that A/C systems were, “use it or loose it.” It is essential that the compressor is run throughout the year to circulate refrigeration system lubricant which keeps seals, hoses and compressors lubricated and fresh. This prevents unnecessary wear on the system and prevents seals and hoses from becoming brittle which then allows them to allow refrigerant to escape.

So, use your A/C without fear, as you are doing both it and yourself a favor by utilizing it.

[Walker1]

Originally posted by aaf709@Mar 6 2006, 12:20 PM
Could you ask her what page it is in the manual? That way we could look at it and see why she interpreted it that way.

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I will do that when I get home. I am married to her, but didn't ask her what page it was. I'll find out later. I'm more inclined to think it goes back to the VW her father had in 1963. I remember the stupid bug had a radio that stayed on when you shut the car off. So, she thinks the Prius is the same. I did show her the 1st few posts on this subject and her response was "Oh, it looks like they might be right." I will find out if there is a page in the manual that tells the owner to turn everything off before putting the Prius to sleep.

I've been married for 25 yrs. and learned being right isn't that big a deal.

[aaf709]

Originally posted by Walker1@Mar 6 2006, 11:00 AM
I've been married for 25 yrs. and learned being right isn't that big a deal.

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True enough. :P As Jeff Foxworthy said, "The first rule of marrige is that if she's not happy, you're not happy." No reason to cause any problems over something like this. Yet the more you know about the Prius the better you are. I did things based on cars I've owned before and found out I was in error.

[Walker1]

It turns out that my other half did not find any info in the owner's manual. It was an assumption on her part. I knew that VW Bug radio issue had to be in there somewhere.

[Tripod137]

Originally posted by lwillis@Mar 4 2006, 09:23 PM
I leave the HVAC system in Auto, but as it is winter time, I keep the AC on off. I've noticed about 2 mpg difference.

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But if it is cool out, the A/C won't actually come on, so how does that save gas?
I thought the A/C light was on to tell you that the system will be activated if necessary, but otherwise is "just as off" as if you turned it off manually, yes?