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This is my second winter of driving my Volt. I did not realize last winter that I could get heat with Fan Only. I always used ECO to get heat. My drive is 56 miles round trip and I usually get 28-34 electric miles when the temperature is in the 20-30s. This winter, by chance, I selected FAN ONLY after the engine had been running for a while and I got great heat. So now I set my ERDTT setting to 35 degrees, FAN ONLY, and temp of 76. I set the fan to medium and vents to split (up and down). Also, use heated seat. Air recirculation off.

Just thought I would let any new owners know the heat is just as hot with FAN ONLY and it is with ECO or COMFORT if your engine is on.
 

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Thought this was common knowledge :)

Fan only is like how a regular ICE car would run. Dependent entirely on the heater core/outside air temps
Comfort supplements with electric heater, and eco uses a smaller amount of electric heat.

Depending on your settings and the temp of the engine coolant, you probably had the same effect as using fan only as the engine would keep the coolant temp higher than the electric heater setpoint (I.e. electric heat never turned on despite being in eco)
So probably no noticeable difference in efficiency between eco and fan only.
 

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We had our 2014 Volt last winter in all the snow in Indiana that never left & now this winter with our new 2015 Volt. We found with both cars the heated seats are all we need except when it is below zero then it is ECO mode. The 14 had cloth seats & after about 15 minutes with stepping the seat heat down to the lowest setting & then off was more than enough to keep us warm - the seats retained heat for quite awhile after turning them off. Now the 15 has leather seats & we can only last about 10 minutes of stepping the seat heat down & then OFF! The leather seats retain that heat way longer than the cloth!
 

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Fan only cooling works at times too :)
 

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Thanks for the info. I was not aware that using fan only would produce heat. Later aceinsp
 

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Fan only will cause the engine to cycle on more frequently, thus reducing your electric miles. (You will be warm however!!)
 

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The only annoying thing I have found with fan only while the engine is running is you can get engine heat when you don't want it. If it is nice outside (70s) I would put it in fan only on my drive in thinking I would get just that: fan ONLY with outside air. But, you get engine heat. So I have to turn off recirculate, and turn down my temp gage to get it to not do that. Which was not intuitive - I assumed fan only was just that: outside or recirculated air, with no temperature modifications done to it. Sometimes the Volt is too smart for its own good.
 

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I think there is more to this than meets the eye -- with my '12 Volt, as an experiment, I did NOT turn on any heat when the car started cold and ERDTT had kicked in. Even after ERDTT had run a cycle while driving I kept the heat off. Only once ERDTT stopped, and I figured the heater core would be hot from engine coolant, did I turn on Eco auto. Nothing -- freezing air for many minutes and the electric heat icon illuminated.

Only after several minutes of electric heat did the warm air kick in -- even after the engine had first been running. Someone on here earlier posted that it may be to prevent the mix valve from opening and sending cold coolant to the hot engine block(?).

It would be nice if an engineer could explain this.

Basically what I think this means is that from a dead cold start, one must first warm the heater core electrically, before the mix valve is allowed to open and mix the heater coolant with warm engine coolant. Only then will ERDTT allow waste engine heat to flow to the heater core and continue to keep you warm on Fan Only.

Correct/Incorrect?
 

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Fan only will cause the engine to cycle on more frequently, thus reducing your electric miles. (You will be warm however!!)
The above statement is not correct on 2013 and newer cars, once warm my car does not use electric heat on any setting.
 

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Only once ERDTT stopped, and I figured the heater core would be hot from engine coolant, did I turn on Eco auto. Nothing -- freezing air for many minutes and the electric heat icon illuminated.

Only after several minutes of electric heat did the warm air kick in -- even after the engine had first been running. Someone on here earlier posted that it may be to prevent the mix valve from opening and sending cold coolant to the hot engine block(?).
This doesn't make any sense. The heater core is part of the engine coolant loop when the engine is running, as explained by WopOnTour. GM said ERDTT happens whether the defroster is running or not, because the heat from the engine has to be available at a moment's notice. They say the electric heater isn't hot enough. There is no logical explanation for the air from the heater core being cold after the engine has warmed up, although ClarksonCote has noticed that the cabin heat from the electric heater is warmer than the heat during ERDTT.

If it's true that you need to use electric heat to get the heat from the engine going even after the engine is warmed up, then the whole ERDTT house of cards has no foundation.
 

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Fan only will cause the engine to cycle on more frequently, thus reducing your electric miles. (You will be warm however!!)
I'm not sure what you mean. If the engine is the only source of heat, then it will run more during the trip to keep the coolant warm, depending on outside temperature and fan speed, drawing less energy from the battery. Whether that extends or reduces your electric miles depends on your definition of "electric miles."

At least in 2013 model year Volts, but maybe not in later ones, the electric heat is locked out during ERDTT no matter how you set the climate control, so whether it is set on fan only, eco, or comfort makes little difference. On 2011 and 2012 Volts, the electric heat does run during ERDTT, so fan only can extend the electric range, but burn more gas.
 

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Pretty sure Tom means (for trips that don't use the entire battery), the engine will run more and result in proportionately more gas km/mi than if you had supplemental electric heat (of which behaviour varies by model year)
Not that it will use more battery power.
 

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I have not found that the ICE will no kick in while using just fan unless the air temp is below 35. So for my part of the country it works great. Later aceinsp.
 

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The other day, it was 10F outside and I had HVAC in fan only mode in my 2014. The ICE and the electric were both going 'til everything was warmed up, then only the ICE cycled to keep the battery warm.
 
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