Does ECO mode really reduce HVAC power consumption? What about the stealth "partial recirc?"

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Well-known member
May 6, 2017
I virtually never use ECO mode in my July 2013 Leaf SV. In a "recent" ECO mode thread, it was stated that ECO reduces power consumption by the HVAC system. I briefly tried monitoring this in LeafSpy and did not see a difference in wattage indicated for heat or A/C. I'll admit I spent very little time observing the system, though, before I forgot about the subject. Has anyone less lazy been able to verify whether there is a difference?

And as long as we're on the subject of range-mongering, has anyone seen that the secret "partial recirculation" mode has a real effect on HVAC power use vs the standard non-recirc? I engage that mode fairly frequently, just because I can, but I've never really been convinced that it does anything. Again, I've been too lazy to really work at it methodically.
I've made the same observation years ago in other topics here about the subject. Using LeafSpy, I never saw any difference in power usage in my 2013 or 2020 Leaf when switching between Eco and non-Eco mode.

Re-circulation mode, whether partial or full does indeed make a difference in regards to heating. In my observations, it can reduce power usage by 50% to 75%. Example, my last test when it was 1 F (-17.2 C) temperature outside, using a setting of 68F cabin temperature (heating) required 3,000 watts of power to maintain cabin temperature, using full re-circulation mode reduced power usage to 1,000 watts of power. Switching back to fresh-air mode raised power usage back up to 3,000 watts of power after a short amount of time. Simple physics, takes more energy to heat freezing air.
That makes more sense why I never saw in on my 2013. Does it affect the later S trim models that also only have the resistance heater? I've never tested it in that trim, only ever had models with heat pumps. :unsure:
ECO mode only reduces power consumption when using the resistance heater (which is all there is on the 2011-2012 MY).
Thanks. Nice to know my brief observations weren't wrong. Pretty sure I had the heat pump mode on.

I'll have to try it again with AC and Heat both on to see if I can catch the resistance heater consumption changing.
I think, what eco mode really does is prevents you from fast acceleration. That is it.
Eco mode does 2 limits motor current ( power), AND it engages the first level of Regeneration. I routinely use the eco button to Slow The Car ! The leaf Should have a 2 postion Toggle on the Wheel for 1st and 2nd level regen ( eg eco and brake modes). As these are our primary means of retarding the vehicle before eventually applying the brakes, and also allows us to optimize regen on downgrades. But will it help with your ac or heat. or when you turtle... not one bit !
Eco mode reduces available acceleration power. I'm not aware of any changes to the HVAC but others can advise on that. You can switch between Eco and normal at any time. E-pedal changes the accelerator pedal into a one pedal mode where electric braking happens when you take your foot off. There is no coasting.
Eco Mode on my 2012 leaf reduces my tork by about 10 percent so I believe it actually drops the voltage supplied to the motor
From my understanding "ECO" mode simply places a little hysteresis (softens) the response of the accelerator pedal. This is likely because electric motors are most in-efficient when just beginning to turn. The result being that the in-rush of current when the motor is beginning to spin up is significantly reduced. This can be effective for squeezing out a few extra miles when driven mostly in a highly stop-n-go scenario (i.e. heavy traffic, city, etc...). I don't believe there's anything to be gained using "ECO" mode on the open highway. However, I believe this softening of the accelerator will also reduce tire wear. I use "ECO" all the time. It's only active during normal driving defaulting to full power if a panic or emergency is sensed (as when the accelerator is pushed aggressively in a "pedal-to-the-metal" scenario).
Eco mode reduces available acceleration power. I'm not aware of any changes to the HVAC but others can advise on that. You can switch between Eco and normal at any time. E-pedal changes the accelerator pedal into a one pedal mode where electric braking happens when you take your foot off. There is no coasting.
In my leaf, it adjusts the pedal curve, but doesn't limit power. If I completely mash the pedal to the floor, I still get full acceleration.

Eco makes a HUGE difference on resistance heat in my 2011. At 0C, the car takes a good 20 mins to warm up in eco mode but ~5m in drive mode.
I wish I remember where I first read that Eco reduces power to the A/C as well as to the PTC. If it doesn't, then it's worth exploring ways of reducing A/C consumption during extremely Hot weather. Since using Recirculate exclusively can cause condensation issues in the system, I guess that Partial recirculation is desirable - even though it probably actually increases power draw in hotter weather.

As for how effective partial recirc is, I don't use it to try to increase range. I use it to minimize intake into the cabin of polluted air, and to reduce windshield fogging.
This is what I can say, observed on a 2015 SL.
Eco has NO Effect on the A/C,ECO on or off the A/C power doesn't change. The amount of power the A/C draws does change with vehicle speed, or more likely air flow over the condenser. At low speed the power is limited to about 1.5kw, once there is enough air flow over the condenser it can rise to over 3kw. Because the Kw useage doesn't suddenly drop when road speed is below 15 Mph or so, I am guessing that the pressure transducer in the high side is used to determine when the power is pulled back.
This all makes sense from a power use standpoint, no point compressing gas to a high pressure that then can't rid itself of heat.
It does reduce the available cooling sitting still or at low speed, but so does not having enough air flow over the condenser. On an engine driven compressor, you don't have as much control as you do with an inverter driven one. Either way you lose cooling capacity at low speed, but the Leafs way means you are not expending more energy to do so.