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03-06-2009, 03:19 AM | #1 |
Drives: toyota yaris Join Date: Feb 2009
Location: australia
Posts: 11
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Using the fan, heater
Sorry if this sounds like a noob question, but will using the fan and heater use up more petrol compared to the fan being turned off. What about compared to the air con instead of heater being turned on?
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03-06-2009, 06:10 AM | #2 |
Drives: 2008 Yaris Liftback Join Date: Oct 2008
Location: South Jersey
Posts: 444
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No. Only the A/C taxes the engine as the compressor has a belt that literally runs off the engine and will drop your MPG about 2-3.....equal to driving fast with the A/C off and the windows open.
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03-06-2009, 08:55 AM | #3 |
Bacon!
Drives: 2008 Red Yaris LB Join Date: Oct 2008
Location: Northern IL
Posts: 45
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FYI
Running the heat on the "Defrost" setting will run the A/C compressor to remove moisture from the heated air. This will cause the same drop in fuel economy as running the A/C to cool the car. If you do a search here you will find a more detailed explanation. |
03-06-2009, 09:14 AM | #4 |
Drives: 2008 Yaris 3-door Meteorite Join Date: Oct 2008
Location: Southeast
Posts: 398
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Which brings me back the one of the things I MOST hate about this car, which is that you can't drive with the ding-dang windows down unless you want banging in your ears; this is crazy car design!!! It's hot from April through October here, so there goes my gas mileage for MOST of the year (I almost never ran a/c in the Swift; windows were always down and life was good). Honestly, I'm not sure I can last long with this car... Yes, I know you can "do things" and "add things" to mitigate that; I paid big bucks (relatively speaking) and would like not to have to remake it to make it work...
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03-06-2009, 11:50 AM | #5 |
Drives: 2008 Polar White LB Auto Join Date: Oct 2008
Location: Metro Detroit
Posts: 1,238
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Ahh your refferring to the infamous "Sonic boom" effect. If one window is completely own, as long as the other one is slightly lowered a bit...the effect isn't really there. I really do plan on getting some of the weather guards for the windows, it's really bad how you can't even crack the window if it's raining since the water will drip right on in.
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03-06-2009, 12:26 PM | #6 |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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Yes, using the heater and fan does use more fuel. The hit is not nearly as large as with a/c but it is there.
The fan requires electricity and the alternator puts more of a load on the engine to produce it. The engine also produces only so much waste heat that makes it into the cooling system, and it often experiences drops in the coolant temperature which causes the ECU to cause the engine to burn more fuel (by running richer and/or at a higher RPM). This means that sometimes you're pulling heat from the system that the engine cannot afford to lose, but other times it is happy to dump excess heat. Sometimes you simply need to use the heat. One should never allow themselves to get too cold in the car. However, like any other use of energy it is best kept to a minimum. Wear a coat and hat and gloves and you'll find you don't need to use the heat nearly as often.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
03-06-2009, 12:44 PM | #7 |
Drives: Yaris 5 door liftback Join Date: Jan 2009
Location: Portland, OR
Posts: 648
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03-06-2009, 02:19 PM | #8 | |
Drives: 2008 Yaris 3-door Meteorite Join Date: Oct 2008
Location: Southeast
Posts: 398
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Quote:
Now back to being positive! |
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03-06-2009, 02:26 PM | #9 | |
Drives: yaris Join Date: Dec 2008
Location: or
Posts: 14
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Quote:
The fan takes up close to zero power, especially at the low settings. It's insignificant compared to the headlights, much less the A/C. |
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03-06-2009, 02:51 PM | #10 |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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colb,
You bring up a good point about the cold enrichment occurrence. I see it rather frequently since I can stay in DFCO for miles on my trip home for work each day and the temperatures, especially at altitude, often dip below 0F. Folks that live in warmer, flatter climes will likely never see it, though. While the blower does not take a huge amount of energy no energy is free, and anything it uses does indeed place a load on the engine. The engine is powered by fuel, ergo any additional electrical load increases fuel consumption.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
03-06-2009, 03:14 PM | #11 |
Drives: yaris Join Date: Dec 2008
Location: or
Posts: 14
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Ah. You certainly can get into situations where the engine gets down below operating temperature then. That is a pretty nasty situation for engine longevity too, if the motor and oil gets cold and is being driven by the car's weight going down a hill. I would coast out of gear and let the car idle for the sake of prolonging motor life (or, if it were me, I might turn the motor off). You're wasting so little gas during idle that you probably wouldn't notice the difference between coasting in gear and in idle.
Which brings me to my next point. The fan certainly does use power, but as usual we need to use our good engineering judgment and ask "how much?" In this case it is at least a couple of orders of magnitude less than the power required to move the car at any speed. Does it use energy - yes. Will it ever use enough energy for you to notice with any common form of measurement, especially gas mileage - no. And in city driving when the car is warm, it's often a toss up between turning the heater and fan on and turning the big giant radiator fan on, which will probably use ten times as much power as the cabin fan. You probably don't have that problem though :D |
03-06-2009, 04:40 PM | #12 |
Drives: 2008 Yaris Liftback Join Date: Oct 2008
Location: South Jersey
Posts: 444
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I don't think so. You have to punch the A/C button to do that.
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03-06-2009, 04:47 PM | #13 |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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No, you don't, and that's the whole gripe that everyone has with it. Whether or not you have the a/c button depressed, if you use either of the dedicated defrost settings the a/c will run along with the heater, simply for the dehumidifying effect.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
03-06-2009, 05:12 PM | #14 |
DWEED
Drives: 3DR 2008 Metorite Metalic Join Date: Oct 2008
Location: Arizona
Posts: 1,161
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Does anyone actually have any proof of the 2-3 mpg loss using the A/C. Last summer I got better mpg using the A/C then I do now with the winter fuel blend. Last summer while climbing a 10 mile long 7% grade at 70 mph I experimented with the A/C. I noticed no power loss while turning it on or no power gain after turning it off.
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Making a decision without following it with an action is still a fantasy. |
03-06-2009, 05:29 PM | #15 | |
Drives: 2008 Yaris Liftback Join Date: Oct 2008
Location: South Jersey
Posts: 444
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Quote:
I'll have to see but I understand what you're saying. My Neon had the constant A/C to defrost which worked great but wasn't always necessary to clear the windows...not to mention it bumping up the rpm's and burning more fuel as consequence.
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03-06-2009, 05:41 PM | #16 | |
Drives: 2008 Yaris Liftback Join Date: Oct 2008
Location: South Jersey
Posts: 444
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Quote:
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03-06-2009, 06:15 PM | #17 | |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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Quote:
Anyone with a ScanGauge can see this in real-time. Within a seconds of turning the a/c system on a noticeable MPG hit occurs. On that grade you likely did not notice a power change because the engine was already at 90%+ load. When that happens I have noticed that the ECU does not allow the a/c compressor to clutch much, if at all.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
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03-06-2009, 06:38 PM | #18 |
Drives: 2013 Chevy Spark 1LT 5-speed Join Date: Oct 2008
Location: Oklahoma
Posts: 1,185
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If it does use extra fuel to run the heater, not enough to worry about. If they tell you that it'll put more load on the charging system and that'll somehow cause you to burn extra fuel...then ...don't run your headlights or wipers, they'll give a big hit to the MPG
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