Air conditioning, Heating
- The LEAF's heating system is similar to that of a vehicle with an internal combustion engine except for the source of the heat. An internal combustion engine generates heat which is extracted by coolant (water and antifreeze). The hot coolant then circulates through a coolant-to-air heat exchanger known as a "heater core". A fan, ducts, and valves direct the air where it is desired. Excess heat is dissipated by the coolant circulating through a radiator. The LEAF differs in that the coolant is heated by a resistive element  which produces only the heat required, so there is never any excess heat to send to a radiator. Because the coolant does not circulate through an engine or radiator, the volume of the coolant used is much smaller (only 1 7/8 quarts ).
- The heater runs if the fan is on and the selected temperature is higher than the ambient temperature.
- evseupgrade.com offers a modified climate control unit (in trade for your stock one) that will have the heater come on only when the climate control is on, and/or the rear defroster is on, and/or the climate control timer engages. (evseupgrade.com is the same outfit that customizes the OEM Nissan EVSE to also work on 240V.)
You remove and send in your stock climate control unit (video instructions here) and they send back a modified climate control unit.
- The LEAF's cooling system is also similar to that of a vehicle with an internal combustion engine except that most vehicles use a mechanical compressor driven by the engine through a clutch. The LEAF, like a few hybrid vehicles, uses an electric motor as a compressor. As in other vapor-compression cycle air conditioning systems, the compressor increases the density, and hence the temperature, of a refrigerant gas. It is then sent through a condenser which extracts and radiates the heat, converting the gas to a liquid state. From there it goes through an expansion valve, which results in it cooling as it returns to gaseous state before entering the evaporator where it collects heat from air being blown past it.
- When in ECO mode, the climate control system operates at decreased capacity to reduce power consumption .
- Diagram of outlets and air mix ratios of various settings of climate control "MODE" button:
Diagram of ventilation duct and its doors, and a table of door positions for various settings of climate control "MODE" button:
- A sun-load sensor  on the dash also provides input to the automatic climate control unit:
"When the sunload suddenly changes, for example when entering and leaving a tunnel, correction is performed so that the recognized sunload of the A/C auto amp. ("amplifier") changes slowly." 
- Replacing climate control microfilter (part number: B7891-1FC0A):
- Replacing cabin air filter
- Another page on how to replace the cabin air filter, at SF BayLEAFs' site, with lots of pics.
- Some people access the filter from below & behind the glove box.
- If you break the filter cover's tab, a replacement cover is US$7 from the Nissan Web site.
- Video showing how to remove and disconnect the center console from the dash, to remove the climate control unit.
- Three ways by BetterLeaf to modify the climate control system to avoid running the heater, with pictures and user feedback. Also further down in the thread are some infrared pictures that show where the heating system could use additional insulation.