Using the fan, heater

[signs]

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?

[NJBob]

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.

[ToddR]

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.

[otterhere]

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...

[detroiter]

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.

[BailOut]

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.

[Yar Is Word]

http://www.yarisworld.com/forums/sea...earchid=433412

[otterhere]

Originally Posted by Yar Is Word

http://www.yarisworld.com/forums/sea...earchid=433412

Something's very wrong with the design if you have to ADD parts to make things work properly. Sloppy and disappointing coming from Toyota, IMO.



Now back to being positive!

[colb]

Originally Posted by BailOut

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.

I think I recall that cold enrichment does not occur above 135F or so on most cars... it's safe to say that your heater will never pump enough heat to get the car into the cold enrichment temperature zone under normal operating conditions. (Actually, I have had this problem in my '85 MR2 when temperatures were below 15F while driving at highway speeds, but that involves problems the Yaris does not have.) The motor produces at least as much waste heat as it does useful work, and even for a tiny Yaris it takes a LOT of energy to push around a 2500+lb metal room on wheels. Using the A/C is using energy you would not otherwise have wasted. Using the heater is using energy that you were throwing out the radiator already, and if the motor is being cooled into its cold-enrichment zone then your radiator has become extraneous.

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.

[BailOut]

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.

[colb]

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

[NJBob]

Originally Posted by ToddR

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.

I don't think so. You have to punch the A/C button to do that.

[BailOut]

Originally Posted by NJBob

I don't think so. You have to punch the A/C button to do that.

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.

[nemelek]

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.

[NJBob]

Originally Posted by BailOut

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.

My bad...I guess. I can't find anything in the owner's manual but when I have the settings on defrost I can hit the A/C button and feel the compressor turn on. When I hit it again, it, of course turns off.

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.

[NJBob]

Originally Posted by otterhere

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...

I agree that you shouldn't have to FIX something to remove the bludgening effect from high speed driving with the windows down. I added the Weathertech Window deflectors which DID ease up the pounding. However if you're driving at 60+ mpg you may as well turn on the A/C. If you have no A/C or prefer not to use it then I'd look into another car and test that bad boy at Hiway speed.

[BailOut]

Originally Posted by nemelek

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.

nemelek,

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.

[1stToyota]

Originally Posted by signs

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?

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