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Air conditioning, Heating


Information

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 [citation needed] 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 [1]).
  • The heater runs if the fan is on and the selected temperature is higher than the ambient temperature.

Cooling

  • 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.

Misc

  • When in ECO mode, the climate control system operates at decreased capacity to reduce power consumption [2].
  • Diagram of outlets and air mix ratios of various settings of climate control "MODE" button:
    Outlets and air mix ratios.gif
    Diagram of ventilation duct and its doors, and a table of door positions for various settings of climate control "MODE" button:
    Ventilation switch pos and door pos.gif Ventilation switch pos and door pos 2.gif


  • A sun-load sensor [3] on the dash also provides input to the automatic climate control unit:
    Sunload sensor P7023623.jpg
    "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." [4]

How-Tos

  • 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.

Problems/Issues





  1. 2011 LEAF Owner's Manual, page 9-2
  2. Nissan LEAF Service Manual, page HAC-23; also 2011 LEAF Owner's Manual, page 4-12
  3. Nissan LEAF Service Manual, page HAC-137
  4. Nissan LEAF Service Manual, page HAC-15