2013 defog mode Heat + AC

So my new to me 2013 has a heat pump and we are getting into our cold season needing to use the defog more often. When I hit the front defog shortcut button on the HVAC controls HEAT + AC illuminate and fan speed seems to be manually controlled. Since this vehicle has a heat pump would it not be impossible for HEAT + AC to be on at the same time?

I can then manually press the AC button and the AC light goes out, HEAT + Front defog stays on and performs about the same.

I'd like to know the most efficient (Both battery wise and utility wise) settings to use the defog modes. I guess I am confused by the HEAT + AC setting on together for a heat pump car.

Your car actually has two heaters: the heat pump and the same resistance heater used by non-heatpump-equipped Leafs. When both heat and A/C are on you are running the power-hungry resistance heater, so avoid doing that. Both heat-only and A/C only settings use less power.

Yep, well I am pretty sure my resistance heater is not running for extended periods at above freezing temperatures so that HEAT button and lamp must have nothing to do with the resistance loop heating.

If I press front defog mod HEAT+AC come on. If I then press AC, the AC lamp goes off but power consumption stays the same and heat still seems to come out.

You can believe me or not, but the heat pump system used in the Leaf cannot both heat and cool at once - that would require more expensive equipment. When both "Heat" and A/C" are on, the resistance heater is running.

vwDavid said:

So my new to me 2013 has a heat pump and we are getting into our cold season needing to use the defog more often. When I hit the front defog shortcut button on the HVAC controls HEAT + AC illuminate and fan speed seems to be manually controlled. Since this vehicle has a heat pump would it not be impossible for HEAT + AC to be on at the same time?

I can then manually press the AC button and the AC light goes out, HEAT + Front defog stays on and performs about the same.

I'd like to know the most efficient (Both battery wise and utility wise) settings to use the defog modes. I guess I am confused by the HEAT + AC setting on together for a heat pump car.

Click to expand...

It depends on how quickly you need to defrost the front window. When press the button, it switches on the AC to pull the moisture out of the air and the electric heat if it needs to heat up the air to your set cabin temperature (depends on outside temperature). So during warm periods, it usually just runs the AC only, but if it is cold outside, it runs the AC + electric heat to keep you from freezing inside the cabin.

If you notice the window is starting to become foggy and have some time, press the vent cycle button to switch to "Defrost + Floor" vent direction, then you can manually use heat or AC to keep the window clear and set the temperature to what is most comfortable.

Both modes vent outside air to help speed up the defrost process, unfortunately, you can't recirculate the air to save energy (if it is really cold or hot outside). In this issue, I've found that using a fresh air dam to block most of the outside air can defrost the window properly and save energy by not having to heat/cool large volumes of outside air. Read more about that here: http://nissanleaf.guru/forum/viewtopic.php?f=9&t=31

To answer your original question though, defrost mode can quickly clear up the window, then switch to a manual mode with a preferred mode (AC or heat) with a low fan setting can keep the window from fogging back up and you stay comfortable temperature wise in the cabin.

I've noticed the same thing, when in defog mode turning on AC, Heat, or AC+Heat yield the same range panelty on the GOM. Therefore I tend to think AC and resistance heater don't run simultaneously. Whatever it is, I find it work really well when both are on, but I'll immediately switch to either defog+foot well w/ AC or turn it off completely.

13MY and newer SV and SL have hybrid heaters. Meaning both heat pump and PTC (resistance coolant heating) types. Here are some tips for how to use the system for best effectiveness.

Intake / A/C / HEAT / Best Used In / Expected Result
Recirc / OFF / OFF / Slightly cool and mild / Retains cabin air. High risk of fogging.
Fresh / OFF / OFF / Mild conditions for vent only / Mild breeze of outside air
Recirc / ON / OFF / Hot weather / Maximum cooling. Lowest A/C power use.
Fresh / ON / OFF / Warm and/or humid / Cooling with fresh air intake. Lowest fogging risk.
Recirc / OFF / ON / Cold and dry / Maximum heating. High risk of fogging.
Fresh / OFF / ON / Cold/cool / Heating with reduced fogging risk.
Recirc / ON / ON / Cold/cool / Heating with reduced fogging risk. High power use.
Fresh / ON / ON / Cold/cool and humid / Heating without fogging. Highest power use.

Many people use recirc and then complain about fogging. Exhaling CO2 and H2O in a closed environment is a natural recipe for fogging. Air circulation and./or air drying (A/C) are necessary to prevent it.

When turning both A/C and HEAT On together the heat pump is not functional. Instead the A/C and PTC heater function together to warm and dry the air.

I hope this helps.