garymelora said:
The car only reports ambient temperature in the upper cluster. The desired setting is a manual input and displayed on the HVAC report screen (lower part of the NAV display) but that is just what you want it to be. The entire system's life is to try and match your desired temp to the "resistance" measure by the In Vehicle temp sensor. Most of the other temps sensors are for system performance and auto mode door settings.
I sniffed the data bus and have yet to find a in-vehicle temp reported. By the looks of it they use this to adjust the blend (air mix) door position by changing the A/C auto amp output signal. Very common HVAC set up. The input circuit has the Ambient temp sensor, Intake temp sensor, In-Vehcile temp sensor, heater fluid temp sensor and sunload sensor report to it. That goes to the processor to figure out the air mix door setting and mode. The processor is on the CAN and LIN bus but I haven't been able to get more than the read the ambient temp.
I just plain do not understand the inability to adjust the 77F preheat/cool setting.
I've got a lot of metal in my back due to a nasty skiing accident, cold really effects me. In my old pass car I hooked up a ceramic heater (into the passenger footwell) and would plug my car in on a timer. Every chilly morning that thing would be nice and toasty. And that thing was only 1500W, the Leaf's heater can draw over 5000W, I love the new preheat settings. Can't wait for colder weather. And seat heater, also a nice option for the metal in my back.
Here is NISSAN's description of the system:
• Input data processing
- Ambient temperature correction
• The A/C auto amp. inputs the temperature detected with the ambient sensor as the ambient temperature.
• The A/C auto amp. internally processes the ambient temperature data is two data types: data for A/C control
and data for ambient temperature display.
• When the vehicle speed is 30 km/h or less, if the effects of radiator heat and other factors result in a sudden
increase in detected ambient temperature, the A/C auto amp. performs delay correction so that the recognized
temperature rises slowly. Correction is performed so that the change is recognized quickly when the
ambient temperature drops.
• When the temperature detected by the ambient sensor is less than approximately –20°C (–4°F), no correction
is performed for the data for A/C control.
• When the temperature detected by the ambient sensor is less than approximately –29°C (–20°F), no correction
is performed for the data for ambient temperature display.
- Interior air temperature correction
• The A/C auto amp. inputs the temperature detected by the in-vehicle sensor as the interior air temperature.
• In order to prevent effects from uneven temperatures inside the vehicle and from external disruptions, the A/
C auto amp. performs correction so that the recognized interior air temperature changes slowly. The A/C
auto amp. performs the correction so that the recognized interior temperature changes according to the difference
between the detected interior temperature and the recognized interior temperature. If the difference
is large, the changes occur quickly, and becomes slower as the difference becomes smaller.
- Intake temperature correction
• The A/C auto amp. inputs the temperature detected with the intake sensor as the air temperature after passing
through the evaporator.
• In order to prevent effects from uneven intake temperatures and from external disruptions, the A/C auto
amp. performs correction so that the recognized intake air temperature changes slowly. The A/C auto amp.
performs the correction so that the recognized intake temperature changes according to the difference
between the detected intake temperature and the recognized intake temperature. If the difference is large,
the changes occur quickly, and becomes slower as the difference becomes smaller.
- Sunload amount correction
• The A/C auto amp. inputs the sunload detected by the sunload sensor.
• 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. changes slowly.
- Set temperature correction
The A/C auto amp. controls the interior temperature so that it is always at the optimum level, and performs
correction so that the temperature felt by the passengers matches the target temperature set with the temperature
control dial, according to the ambient temperature detected by the ambient sensor.
