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Climate Control Unit (CCU)

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Introduction
The Climate Control Unit (CCU) of the NSX controls heating, cooling and ventilation of the passenger cabin. It utilizes several electrical sensors and actuators across the vehicle to do so:

Sensors Actuators
  • Outside temperature
  • Cabin temperature
  • Sunlight
  • Heater core temperature
  • Evaporator temperature
  • Blower Motor
  • Mode control motor
  • Vent door control motor
  • Air mix control motor
  • Recirculation control motor


Self Check
Except for the blower motor, above items can be checked by means of a CCU self check feature. It's activated by pressing both the left (Auto) and right (Off) button on the CCU at the same time. Each character on the display (except "FULL", AUTO" and the temperature value) represents a detected fault.

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No errors dected

To ensure proper detection (especially for motor related issues) the CCU should be run in full automatic mode, then turn the temperature control from lowest to highest in slow steps. This makes the CCU run all actuators and confirm potential issues.

Indicator Fault
MODE Cabin temperature sensor - open/short circuit
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Size:  422 Bytes Evaporator temperature sensor - open/short circuit
A/C Air mix control motor - open/short circuit or door stuck
ON Mode control motor - mode door stuck or position signal circuit
OFF Recirculation control motor - position signal circuit
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Size:  543 Bytes-Button LED Vent door control motor - open/short circuit or door stuck
Note that errors are not stored and will disappear upon ignition-off.


Auto Check Routine
An additional automatic check routine is available by setting the Fan-dial to "AUTO" and pressing both the left and right button at the same time before switching on ignition and starting the engine. Once activated the CCU is cycling through an combination of all settings which can be used to confirm that all of them are working as expected.

Temperature Fan Air Mix Door Mode Recirculate A/C
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Known Issues
Similar to many other ECUs in the NSX the CCU is subject to capacitor leakage and resulting damage. A typical symptom is a fan working on the highest setting only.
If these or other unusual effects are observed and/or the self check shows detected faults which can't be confirmed, action should be taken before the unit becomes irreparably damaged. Preventive replacement of the capacitors is highly recommended.

Updated 14-11-2020 at 10:47 PM by Heineken

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