SierraQ
Posts: 185
Joined: Mon Oct 18, 2010 8:44 am
Delivery Date: 02 Sep 2011
Location: Dallas, TX

Climate Control and AUTO Mode Guide

Tue Jan 31, 2012 2:48 pm

This is an exhaustive explanation of the 2011-2012 Leaf climate control system vs the 2013 Leaf CC system versus other cars (i.e. ICE). This is focused on automatic climate control systems which are becoming more and more common. Feel free to point out additions or errors especially in the 2013 notes as I had to infer those from what I've read!

How to Read This Guide
Each section refers to a button and what it does in various vehicles.
Typical includes typical automatic climate control systems on ICE vehicles and also the Leaf
(year) Leaf lists unique characteristics found in the Leaf. If a year is not given it applies to all models in the 2011-2013 range.

General Notes about Heat
In ICE vehicles heat is a free byproduct from the engine and available once the engine warms. In the Leaf and all other electric-only vehicles heat must be generated and therefore costs energy since the electric engine itself does not produce significant heat to use for the cabin. The 2011-2012 Leaf there exists a PTC (Positive Temperature Coefficient) heater which in simple terms is an electric heater that heats water that in turn heats the air. In the 2013 and later Leaf there is a new hybrid heater which uses the PTC heater but also a heat pump (reverse air conditioning)--this system uses less energy and allows you to shut the heat portion of it off to save even more energy.

AUTO (full auto mode)
Typical
  • Sets temperature, mode, fan speed, A/C, and recirculate under automatic control.
  • Pressing mode, fan speed, A/C, or recirculate buttons will put the system in semi-automatic mode. Only the feature you changed will be fixed, the others will continue under automatic control even though the "AUTO" indicator is no longer lit.
  • Has no effect on heat which is used as-needed.
  • Compressor tends to run for all temps above freezing
Leaf
  • Heat is generated as-needed while in drive mode. (see also: A/C)
  • Compressor runs only if interior temp is less than exterior temp so it is more effecient than typical systems.
Temperature
Typical
  • Selects desired cabin temperature. This works by mixing cool and warm air to achieve the set temperature. If the cabin is 90 and the desired temp is 70 it will likely select the coldest air available until the cabin reaches close to 70. Then it might blow mixed air at 65 degrees to maintain it. The temperature control also influences Mode and Fan speed when they are under automatic control.
  • Contrary to manual systems, the temperature setting does not directly control the mix of air. On a 90 degree day, setting the temperature to 60 will not be any colder than setting it to 70, at least initially.
Mode
Typical
  • Controls where air comes out, everything except 100% defrost (which has a dedicated button) and defrost+vent (mode generally not allowed)
  • Under AUTO heat comes out of floor (presumably because it is more comfortable not to have hot air blowing in your face and that heat naturally rises). Cold air comes out of vents. In-between or close-to-cabin-temperature air comes out vent and floor (bi-level).
Fan
Typical
  • AUTO fan will increase fan speed the greater the difference between set temp and cabin temp.
  • AUTO fan may be off initially if heat is needed because the car is waiting for the engine to warm.
  • Pressing fan while in AUTO will override the fan, all other functions remain on AUTO even though AUTO indicator is not lit.
2011-2012 Leaf
  • AUTO fan may be off initially to allow water heat exchanger to become warm.
2013 Leaf
  • AUTO fan may be off initially to allow water heat exchanger to become warm in very cold temperatures (about 150 seconds according to manual).

A/C
Typical
  • Turns on compressor for temps above freezing, hence the popular correlation between "A/C" and "cold air" although this is technically incomplete as heated air could also be called "conditioned."
  • The A/C mode is automatically engaged when any defrost mode is selected so as to dehumidify the air.
  • The A/C mode is automatically engaged when recirculate is selected again to dehumidify the air (your own breath will fog up a car in a hurry) or in some cases it assumes you want "Max A/C".
2011-2012 Leaf
  • A/C (via AUTO) must be engaged to get heat if you are charging the car, but not while driving (though some would wish it so). In other words if you turn the A/C button off during charging, the heat will shut off too.
  • A/C (via AUTO) does enable the compressor but where most cars seem to run it liberally (even if it is 50 degrees out) the Leaf is smarter about this and only runs it when the set temp is lower than the external temp.
  • There is a forced-A/C mode (toggle A/C off then on) which will force the compressor on even when not needed.
2013 Leaf
  • If heat and A/C buttons are both off then the Leaf is in vent-only mode using negligable energy.
  • Assumption: The behavior is otherwise the same as the 11/12 Leaf except that the A/C button no longer controls heat as there is now a new "heat" button for that. (I have no 2013 Leaf to test to confirm this.)
Heat
Typical
  • Not applicable
2011-2012 Leaf
  • Not applicable
2013 Leaf
  • If on, forces heat on via heat-pump and/or PTC heater as needed.
  • If heat and A/C buttons are both off then the Leaf is in vent-only mode using negligable energy.
  • If heat and A/C buttons are both on this enganges "dehumidified heat mode" which forces on both the compresser ro dehumidify and the PTC heater to heat. This uses the most energy and may be necessary if the AUTO heater is fogging up the windows.
Defrost (front defroster)
Typical
  • Directs all air to defrost vents. Turns on A/C (for compressor) to dehumidify. Turns off recirculate to avoid humidity. In some cases fan speed is also increased.
  • Pressing the button again either does nothing or more commonly (including in the Leaf) reverts the system to its previous settings.
Recirculate and Fresh Air
Typical
  • Selects source of air.
  • Max A/C (if equipped) is basically A/C plus recirculate
  • Defrost mode forces Fresh Air
Leaf
  • Holding down the currently selected mode for a few seconds until they flash basically puts this button back into automatic mode if you manually overrode it. This is a curiosity as you cannot do something similar with Fan or Mode without hitting the AUTO button.
FAQ
  • Can I run vent-only to save energy?
    2011-2012 Leaf] No. The heater will come on if the cabin gets cold enough and 60 degrees F is the lowest you can set the climate control to. There is no known way to get around this in a stock 2011-2012 Leaf. You can purchase a modified control unit the Ingineer has created which will allow you to run vent-only. See http://www.mynissanleaf.com/viewtopic.php?f=37&t=6751" onclick="window.open(this.href);return false;

    2013 Leaf] Yes. Make sure A/C and Heat lights are off. The car will be in vent-only mode.
  • How do I get heat/cool if the Leaf is connected to power? Make sure car is charging. Place the car in ON mode (press power button twice w/o brake). Press AUTO and/or make the A/C indicator is lit. Heat/compressor may not come on until Leaf reaches at lest 20% power. Note that the A/C light (or the Heat light in the 2013 Leaf) must be on for heat to work in this case. Again, the car must be charging. Simply being connected to a power source is not enough--for example if you are on a charging timer that hasn't triggered yet.
  • Why does the heat not come on immediately? Many cars with automatic climate control including the Leaf do not turn the fan on until sufficient heat is built up under certain conditions. You can force it on by selecting a fan speed.
  • How long does remote climate control run? 2 hours if plugged in; 15 minutes if not. It will not start if the battery is very low.
  • Can I leave the A/C or heater on for a passenger/pet? To do this for longer than the 15 minutes you get with carwings you have to leave the car on in ready to drive mode. You can take the fob with you and lock it with the remote. Do keep in mind that the car can be driven without the fob if it has already been started. (If you happen to be charging, the car must only be in ON mode and hence it cannot be driven.)
Tips
  • There does not appear to be any savings in running AUTO w/o A/C in the winter. The Leaf, unlike many cars, does not run the compressor needlessly in full AUTO mode. So you can safely use AUTO during significantly warm or cold days. (I have not experimented much with temperate days.)
  • With climate control off you can still place the Leaf in Recirculate to mostly seal off outside air which will better prevent cold air or undesirable fumes from coming in. However, it does tend to cause more window fogging.
  • With climate control off you can still choose a Mode (if you want the ambient air flow to go somewhere else) without turning on the fan or consuming any power. The fan will read zero speed.
  • ECO mode reduces the power consumption by the climate control system but at the expense of less heating/cooling performance.
  • The "turn climate control on/off for +/- miles" message is an estimate and does not take into account actual power use initially. For example if it is 65 degrees out and you set your system to 60 w/o A/C you will have vent-only, no cooling, no heating, yet the system will still say you are losing miles. This is not accurate because the fan alone does not use significant energy. (Note: not sure if this is fixed in the 2013 Leaf.)
  • You have no control over the remote control or timer-based climate control function other than ON/OFF. You cannot set the temperature, mode, or anything else.
  • Remote climate control will not work if the battery is low.
  • Remote climate control heating is notably weaker on the 120V L1 charger compared to the 240V L2 or fast charge.
  • There is some scenario where you want A/C while charging but the compressor will not engage. If this happens to you try restarting the car and/or climate control system and it should come on (assuming the battery is not critically low.)
Last edited by SierraQ on Wed May 29, 2013 3:47 pm, edited 6 times in total.
"Please tell me this doesn't run on gas! Gas explodes, you know?" --Susan in I-Robot

occ
Posts: 267
Joined: Thu Jun 24, 2010 1:14 pm
Delivery Date: 26 Jun 2015
Location: Tustin, CA

Re: Climate Control and AUTO Mode Guide

Tue Jan 31, 2012 4:42 pm

Thanks SierraQ. I could never understand how to use the LEAF auto climate control when sitting in the LEAF and playing with it, and too lazy to look through the manual. I've booked-marked this thread in case I need a quick guide.
2011 Nissan LEAF:
Res: 4/21/10 7am
RAQ: 11/23/10 (& ordered)
Delivered: 6/17 vin 4873
Toyota Rav4EV (2/27/13)
4Kw Solar PV

EatsShootsandLeafs
Posts: 649
Joined: Fri Aug 24, 2012 10:59 am
Delivery Date: 24 Aug 2012

Re: Climate Control and AUTO Mode Guide

Tue Sep 11, 2012 12:18 pm

occ wrote:Thanks SierraQ. I could never understand how to use the LEAF auto climate control when sitting in the LEAF and playing with it, and too lazy to look through the manual. I've booked-marked this thread in case I need a quick guide.
Yep, this is helpful.

User avatar
Ingineer
Posts: 2741
Joined: Fri Oct 15, 2010 1:09 pm
Delivery Date: 13 Jul 2011
Leaf Number: 6969
Location: Berkeley, California
Contact: Website

Re: Climate Control and AUTO Mode Guide

Tue Sep 11, 2012 4:57 pm

SierraQ wrote:FAQ
  • Can I run vent-only to save energy? No. The heater will come on if the cabin gets cold enough and 60 degrees F is the lowest you can set the climate control to. There is no known way to get around this in a stock Leaf. You can purchase a modified control unit the Ingineer has created which will allow you to run vent-only. See http://www.mynissanleaf.com/viewtopic.php?f=37&t=6751" onclick="window.open(this.href);return false;
Thanks Sierra for the excellent FAQ! (and the plug) This should definitely be a sticky somewhere!

Note that he have the aforementioned Energy-Saving HVAC module upgrade in stock for $138 and available for immediate shipping. If interested, please contact us to place an order. (We do not have this listed on our web site yet)

Image
-Phil
Easily Learn Electricity HERE! - - - - Website: http://evseupgrade.com/[/size] - - - - Like us on Facebook: EVSE Upgrade

User avatar
dgpcolorado
Posts: 3124
Joined: Sat Aug 20, 2011 1:56 pm
Delivery Date: 15 Dec 2011
Location: The Western Slope, Colorado

Re: Climate Control and AUTO Mode Guide

Wed Sep 12, 2012 4:06 pm

^Ingineer's modified CC unit is well worth it for those of us in cold weather areas: It was cold, damp, and rainy this morning and I was able to just blow air at the windshield to reduce fogging by selecting defrost and then turning the AC button off. When that wasn't enough I could briefly (seconds, really) turn the AC button on until the windshield fully cleared and then turn it off again and leave air blowing on the windshield.

Of course the real advantage of the modified unit is the ability to use the CC system—fans, vents, and the like—and have the power-hungry heater off. Pre-heating while plugged-in plus the steering wheel and seat heater is plenty for comfort where I live.

-Happy Customer
Blue 2012 SV Dec 2011 to Feb 2016
CPO 2014 Tesla S60 Mar 2016
One car, no ICE, at last!
Tesla Referral Code

Becky50
Gold Member
Posts: 166
Joined: Mon Apr 02, 2012 9:42 pm
Delivery Date: 02 Aug 2012
Leaf Number: 019032
Location: San Jose, CA

Re: Climate Control and AUTO Mode Guide

Thu Oct 11, 2012 1:30 pm

SierraQ, Thanks for the detailed, clear explanation. With the colder weather approaching, this is just what I was looking for.
Becky50

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: Climate Control and AUTO Mode Guide

Thu Oct 11, 2012 7:18 pm

One point you make (or really, don't make) seems contrary to what I have believed. Most cars do indeed mix cold and warm air to achieve the requested temperature. But are you sure the LEAF does that when heating the cabin? Most cars can't control the temperature of the coolant, so the only way to reduce heat is to reduce air flow over the exchanger. But the LEAF can cycle the heating coil to get the exchanger to the temperature you want. There should be no need to mix in cold air.

Note: I'm not speaking from internal knowledge, only from what "seems" like it should be logical. So I'm asking, not stating.

Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

SierraQ
Posts: 185
Joined: Mon Oct 18, 2010 8:44 am
Delivery Date: 02 Sep 2011
Location: Dallas, TX

Re: Climate Control and AUTO Mode Guide

Tue Feb 19, 2013 11:29 am

planet4ever wrote:One point you make (or really, don't make) seems contrary to what I have believed. Most cars do indeed mix cold and warm air to achieve the requested temperature. But are you sure the LEAF does that when heating the cabin? Most cars can't control the temperature of the coolant, so the only way to reduce heat is to reduce air flow over the exchanger. But the LEAF can cycle the heating coil to get the exchanger to the temperature you want. There should be no need to mix in cold air.
Interesting point. I do not know for certain. Likely it is as you suggest that the Leaf is reducing the power to the heating mechanism rather than mixing in some cold air. This would be more efficient and would seem to agree with the power consumption of heat over time. However, it's not that important to my point and I didn't want to speculate. The point I was trying to make is that you don't have control over the raw vent temperature like you did with the old mechanical control systems. This is to explain why the vent temperature will change as the cabin approaches the set value and the Leaf behaves like "most cars" in that way regardless of how it is accomplished.
"Please tell me this doesn't run on gas! Gas explodes, you know?" --Susan in I-Robot

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: Climate Control and AUTO Mode Guide

Tue Feb 19, 2013 2:42 pm

One other very minor point under "Fan": Technically the fan isn't waiting for the electric heater to warm; that happens very quickly. It is waiting for the heater to warm a half gallon or more of "coolant" (heatant?) which is used to transfer heat from the electric heater to the heater core where it can be used to heat the air.

Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

EV1
Posts: 43
Joined: Sun Apr 07, 2013 1:50 pm
Location: The Netherlands

Re: Climate Control and AUTO Mode Guide

Thu Apr 11, 2013 12:53 pm

Thanks for this elaborate guide!

"Unlogical" seems to be the nicest thing one can say about CC system of the 2011/2012 Leaf!
I spend some time learning how to use the CC and really, really, it's hard to believe this was actually engineerd / designed the way it is.
But this has been discussed alot in other posts also.

@planetforever:
I can confirm the Leaf uses mixing of air when heating. Found that out on one of my evenings "playing" with the CC. You can hear the mixing valve changing when going from a certain temperature to a higher one. (fan on lowest speed, both temps need heating)

Return to “Tips & Tricks”