Keep your car de-fogged without using the heater

[uwskier20]

I've found that moisture builds up in the upholstery. Running the heat full blast for a while (30-40 minutes), then opening the windows, seems to help dry the car out. I do this every few weeks in the fall/winter while plugged in.

 

[camasleaf]

Maybe it has been posted, but I did not know: When in windows defog mode and while charging you can disable/enable the heater by pushing the AC. Not very helpful unless you are in the car while charging, and want to clear the windows without using the heater in order to charge faster.

 

[vanagon]

The A/C compressor does run in Defrost mode, and cannot be turned off. However in Foot/Def mode I am pretty sure it can be turned off. Same logic every Nissan uses.

In our Nissan S (2013), both the A/C and the Heat can be independently turned on/off in Defrost mode. (When you first push the defrost button, both are in the on state by default). If the window starts out clear and the car isn't fully loaded with humidity-producing humans, defrost mode with no A/C and no heat on the lowest fan setting tends to be enough to keep it clear.

The one thing you are absolutely not able to do---even in foot+windshield mode---is turn on recirculating air. Presumably it would result in a very quickly fogged window in cold weather. I have wondered though, whether one would be able to get a way with heat+A/C (for drying)+recirculate to both heat the car efficiently (recirculating air) and keep the window clear. I'll never know!

 

[Goodtohave]

I hate to say it but 5 pages on saving consumption on defrost ....

For the sake of "effeciency" couldn't this have been done in one page

 

[FalconFour]

The one thing you are absolutely not able to do---even in foot+windshield mode---is turn on recirculating air. Presumably it would result in a very quickly fogged window in cold weather. I have wondered though, whether one would be able to get a way with heat+A/C (for drying)+recirculate to both heat the car efficiently (recirculating air) and keep the window clear. I'll never know!

I've done this, actually - heat + A/C + recirculate + bi-level mode (face + feet). Seemed to work pretty well, but the moment you switch off the A/C, the condensation built up on the A/C coils just goes right back into the air with gusto, like a humidifier just turned on instead.

I do Uber rides in my Leaf now, and I need to balance power consumption with keeping riders comfortable. I switch off CC while I'm between calls since I can handle a cold car, but it's sometimes a trick to get the interior cozied up when I'm on the way to the next pickup... people just aren't used to a car that's not blaring heat produced by the car's engine...

 

[HyperMiler]

The A/C compressor does run in Defrost mode, and cannot be turned off. However in Foot/Def mode I am pretty sure it can be turned off. Same logic every Nissan uses.

In our Nissan S (2013), both the A/C and the Heat can be independently turned on/off in Defrost mode. (When you first push the defrost button, both are in the on state by default). If the window starts out clear and the car isn't fully loaded with humidity-producing humans, defrost mode with no A/C and no heat on the lowest fan setting tends to be enough to keep it clear.

The one thing you are absolutely not able to do---even in foot+windshield mode---is turn on recirculating air. Presumably it would result in a very quickly fogged window in cold weather. I have wondered though, whether one would be able to get a way with heat+A/C (for drying)+recirculate to both heat the car efficiently (recirculating air) and keep the window clear. I'll never know!

As stated above, most of the discussion in this thread is incorrect.
Both in the 2012s and 2013s, you can run a minimal effort defrost by pressing defrost first, disengaging AC, winding down the propeller to minimum (which is more important for energy use than the temperature setting) and wind down the temperature to minimum if you really need to. Works very well, and comes back on when restarting the car, unless you go to a different mode in between.

Always keeping in mind that the prop speed determines how much air is pushed through the car and needs to be heated. The temperature setting can be cozy, as long as the prop is low.

Other very effective measures: use an umbrella and stick that plus your coat in the trunk, and blow dry your hair at home...

Best,

HyperMiler

 

[Nubo]

Always keeping in mind that the prop speed determines how much air is pushed through the car and needs to be heated. The temperature setting can be cozy, as long as the prop is low.

The amount of heat (thus energy) will be determined by the thermostat (not the fan), up to the point where the airflow won't support the heat transfer. If the desired cabin temperature is being reached, fan speed has little bearing on energy used other than it may disrupt still air near the windows and thus increase heat conduction to the outside.

Take the "energy info" display with a grain of salt.

 

[HyperMiler]

Always keeping in mind that the prop speed determines how much air is pushed through the car and needs to be heated. The temperature setting can be cozy, as long as the prop is low.

The amount of heat (thus energy) will be determined by the thermostat (not the fan), up to the point where the airflow won't support the heat transfer. If the desired cabin temperature is being reached, fan speed has little bearing on energy used other than it may disrupt still air near the windows and thus increase heat conduction to the outside.

Take the "energy info" display with a grain of salt.

I beg to differ, your honor. That is true only if Auto controls both temperature and fan speed.

If the fan speed is a given, it controls the amount of (outside, cold) air that is being heated.
You are literally blowing heated air out the back at the rate you are sucking cold air into the front.

Which is several fold higher in the high settings than in the low settings. The influence of the inside temperature chosen (e.g. 68 vs 74) is far less critical.

The loss of actual mileage is greater if you run a modest temperature on a significant blower speed as compared to a cozier temp on the low fan setting (which is more effective at removing humidity from the front windscreen, too).

 

[Nubo]

Always keeping in mind that the prop speed determines how much air is pushed through the car and needs to be heated. The temperature setting can be cozy, as long as the prop is low.

The amount of heat (thus energy) will be determined by the thermostat (not the fan), up to the point where the airflow won't support the heat transfer. If the desired cabin temperature is being reached, fan speed has little bearing on energy used other than it may disrupt still air near the windows and thus increase heat conduction to the outside.

Take the "energy info" display with a grain of salt.

I beg to differ, your honor. That is true only if Auto controls both temperature and fan speed.

If the fan speed is a given, it controls the amount of (outside, cold) air that is being heated.
You are literally blowing heated air out the back at the rate you are sucking cold air into the front.

I stand corrected. Hadn't thought about the air being expelled in non-recirculate mode.

 

[HyperMiler]

One more fun fact: the Mode button works with the heater off, i.e. the passively moving air enters through the opening you select.

 

[BrockWI]

And if the last thing you select is defrost and turn it "off" the air will still naturally vent through the last selected location assuming you ahve enough forward speed to naturally move the air

 

[donald]

For cars with heat pump heaters, in theory (AFAIU) there should be no need, and in fact a loss of efficiency, in turning off the AC with heat.

The AC works by drawing heat out of the cabin air, and condensing out any water. In the Leaf heat pump circuit, that same working fluid is then recondensed in the second condenser matrix, the 'heater', in the dash.

So any heat you pull out with the evaporative matrix is recovered in the condenser matrix. You're actually using the car's warm air as the 'warm-source' for the heat pump! The heat from the condenser matrix is then, in effect, simply the mechanical power delivered to the working fluid by the pump, and any heat it may gain at the front matrix (now acting as an evaporator).

However, as the cycle includes a cooling phase where the humidity is condensed out, you can now run recycle, and therefore vent none of the warmed air out of the car. Running recycle and AC would therefore now be more efficient than not running the AC and taking in outside air.

Further still, as you condense out the water vapour, you are pulling some of that thermal energy into the working fluid, and expelling the now lower-energy condensed water. You'd actually be taking advantage of the warm foggy humidity you and your passengers are emitting by drawing heat out of it!