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Climate Control Unit (CCU) - Repair

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Failure of the Climate Control Unit (CCU) is a common fault, affecting nearly any NSX. In almost any case, capacitor replacement and track repair will fix all issues. Depending on the state of the PCB, further damage to other components can happen, though.

The following error cases and ways of repairing have been identified so far. These faults can be caused by major acid leakage affecting nearby transistors.

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Interior fan working only in automatic mode
If that's the case, regardless of the dial setting (don't mistake it with a CCU that works only on the highest dial setting) it can be related to a faulty Q17. The transistors Q14 to Q17 are level shifters providing the position of the fan speed dial to the large Microcontroller.
They are NPN transistors with an internal 4.7 kΩ base resistor (NEC A1L3Z). Such parts are no longer available as a direct replacement but still sold in SOT 323 SMD packaging (ADTC143TUAQ) - which requires appropriate adaptation work (SOT23 adapter PCBs):

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AC Compressor and Fans not coming on
.. even though they should (AC isn't OFF) can be caused by a faulty Q9 or Q10. This transistor (NEC AN1L3N) is a PNP type with two integrated resistors: 4.7 kΩ (R1) at the base and 10 kΩ (R2) from base to emitter. Same as with Q14 to Q17 there are no drop-in-replacements available anymore. A possible SMD replacement is PDTA143X with corresponding adapter PCBs:

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Updated 22-05-2022 at 04:07 PM by Heineken

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