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Today at Atelier Kaz - Private NSX Enthusiast, ex-Honda R&D engineer with F1, Indy/CART background

A/C CCU Board service 03

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When I first received this CCU board, I was worried about the damages to the big IC1 based on so many components being bent, etc.

However, the self diag worked fine and even the logic of function & operation check were carried out without any issues that IC1 was very unlikely to be damaged.

Just the fan speed control.

So, started looking into the cause and as mentioned above, found at least 2 components that were fine when tested on the circuit board but turned out they had intermittent continuity due to cracked lead.

As it was not cost effective to try repairing this board, asked the owner for the extra time in order to search for another used CCU board while deciding to limit the cost for repairing this board,
just like I did in the past as it became more of my own challenge and interests.

So started removing each components for further inspection and while some of them were suspicious or faulty, none of them were related to the fan speed control.

This was when I contacted BrianK.

At the end, based on Brian's suggestion, I just removed all zener, diode and nearby resistors at the green connector and while none of them were faulty, replaced with new one or known good ones.

This fixed the issue but still 100% not sure on the exact cause as none of the removed components were faulty and even checked all of the continuity of the through holes at each components mentioned above before removing them.

Anyway, after weeks of challenge, the board was ready for the 50miles of test driving session using my NSX.

This will allow me testing under the real driving environment such as the EMI, IG/alternator noise, thermal shock, vibration, etc.

After passing all test scenarios, if something doesn't work on the owner's NSX, it is most likely that something outside of the CCU.