CCU Computer board Service - Part 1/3

[WhyOne?]

A long overdue public 'thank-you' to Kaz.

Kaz kindly removed the CCU from my (2001) car on the Sunday of the Silverstone Classic. The CCU was back with me by the following Wednesday, but it has taken until today for me to replace the unit in my car.

Needless to say, thanks to Kaz's meticulous attention to detail, everything works perfectly.

Symptoms of developing CCU board problems in my car were very subtle - at the lowest setting the fan sometimes 'fluttered' and I was unsure that the transition from cold - hot was quite as gradual as it should have been.

Kaz reported that a number of the capacitors had started to leak, though there was no damage to the circuit board from this leakage - so caught them just in time!

The fan no longer flutters, and there is a much more progressive change from hot - cold - hot.

As a very reasonably priced piece of preventative maintenance I cannot recommend Kaz's service highly enough.

[Kaz-kzukNA1]

Hi, 'WhyOne?'.

Thank you for the generous comment and I'm glad you are enjoying the refurbished CCU.

From what I saw in the past, it was not possible to detect any CCU internal failure unless you opened the unit.
Because of this, many owners are running their NSX with CCU issues without being noticed. By the time the owner started to experience even the tiny issue, the damage was already made.

I also serviced the CCU from 2004 NSX and there was already small amount of leakage from the capacitors.
Yours is 2001 model and again, there was enough leakage to cause the issue on climate control.

I hope every owners will have their CCU serviced before it's too late.

Regards,
Kaz

[Kaz-kzukNA1]

Hi, all.
Just wanted to say thank you to everyone who used my Air Con (A/C) Climate Control Unit (CCU) Computer board service in the past.

I would like to share some of the findings so far based on the UK spec.

1. Changes on A/C CCU Capacitor spec
For UK model, the spec of the aluminium electrolytic capacitors used inside the CCU was upgraded around 97.
Therefore, if your NSX is upto and including 96, it is highly likely that you already have some issues with your CCU board. As you can see from my previous post, quite often, the damage was already done even without being noticed by the owners.

If you know how to remove the CCU and deal with electrical circuit board, you can do a quick check on the spec of capacitors. If your CCU board was never serviced in the past, check the colour of the capacitor (cylinder like) body used at C44.

If it is in Black, then you have the old spec and almost 100% guaranteed to experience capacitor failure by now.
The new spec capacitors are in Brown.

2. CCU board from 1997 and onwards
Even you have the new spec capacitor board, you are not free from the failure.

It all depends on the environment factor (especially, the temperature) around the CCU.
I don’t know the exact number of UK NSX from 97 onwards but I presume it is limited.

Even within this limited number of NSX, I already saw severe capacitor issues on 98 and 99 models. There were several issues even on 01 model but at the same time, no issues with some of 00 ones. One of the best board (but still showed tiny leakage) that I saw was from the 04 model.

If your NSX spent long period in hot summer country or if you have aftermarket audio head unit with built-in amplifier, the CCU board seemed to fail earlier than usual.

3. The level of damage

So far, I managed to fix all CCU board but more and more, it is taking extra time on older cars. Recently, I started to spend more time fixing the area around DM11 close to C44 due to the leakage from this capacitor. DM11 is a diode array and as it is not Rohs compliant, it is no longer available as an aftermarket parts. It has to be replaced with same spec surface mount module with jumper wire instead.

Also, the circuit tracks around DM11 were damaged regularly and required several repair work.

As mentioned in the past, by the time when you start experiencing the issue with you’re A/C, the damage would be severe.
Some people ended up with no lights on the display, fan operated only at High, no air temperature control, A/C started to operate even the CCU was switched off, etc, etc….

Please have your A/C CCU board serviced before it’s too late.

Oh, and once again, even in the winter, please keep using your A/C.

It is important to circulate the oil inside the A/C system for the compressor. If you keep manually selecting the ‘A/C OFF’ option by pressing the ‘A/C’ button, you may end up spending more than GBP1,000 instead of trying to save small amount of fuel.


Regards,
Kaz

[AR]

Kaz how much power does the NSX loose when the AC is on is there a detrimental effect to the AC clutch at high rpms?

Many thanks,

Ary

[Kaz-kzukNA1]

Hi, Ary. Apology for the late reply. Trying to catch up with so many backlog at the moment...

I have never measured the power loss by the A/C on the dyno but it won't affect at high rpm.
The A/C Control unit is receiving rpm signal from the ECU and I won't be able to provide you with the definite figure but the A/C will be disabled above certain rpm such as 4,000 - 6,000rpm.

Depending on the circuit shape, the rpm may drop below this threshold so it would be best to switch off the A/C during the track session. Please remember to switch it back on after the session.


Regards,
Kaz

[AR]

Many thanks for the info Kaz, whenever driving the car in a spirited fashion, I always turn off the AC.

[henry_mac]

I just got my NSX back today from Kaz who had been doing some work on it following on from a recent health check.
The CCU was functioning ok and passed diags at the Health Check but given the known electrolyte leakage problems I thought it prudent to have the CCU serviced - glad I did. There was a lot of leakage and damage to the board, all of which Kaz repaired. The unit is functional again and has a new lease of life.
I also had my 3 Amp's reconditioned as the Bass sound was not good and I must say that I am mightily impressed by the sound quality now. I had a PA11-HON fitted at the same time and now have my music collection from my Iphone playable through the OEM Unit.. i love it.. works like a dream.
Kaz will post some pictures of the issues from the above and also the brake service (my brakes were in a bad way) it's great to have back my stopping power thanks to Kaz's magic. I can't recommend Kaz highly enough, his quality of work and perfectionist attitude is second to none.

Henry

[Kaz-kzukNA1]

This time, it was the 96 UK spec Targa model.

The owner didn’t feel any issues with his A/C CCU control and it also passed the self diagnosis test.

However, because it was 96 model, I assured the owner that the CCU would show several issues and we agreed to carry out the refurbishment service.

After opening the box, it was quite obvious that the board was in really bad shape and once again, the owner didn’t notice any issues…


The leakage from C19 was left so long that it dissolved several tracks and pads. Also, it caused intermittent connection on nearby resistor R19. While measuring the resistance, the value was changing and sometimes showed open circuit so decided to replace it with the new resistor.

[Kaz-kzukNA1]

The area around C44 was also very bad and although the leaked acid covered the resistor array and diode module, it didn’t take them out… It was also close to the big IC so I’m glad we acted now.


Some of the tracks were already dissolved and they were almost open circuit so had to use jumper wires to recover the connection.



Once again, please act before it’s too late.

[Kaz-kzukNA1]

While the centre console was partially removed for CCU service, I also asked the owner if I could clean the Cabin Temperature sensor because the aspirator fan was making very annoying noise.


It was covered in so much dust that I couldn’t even see the sensor head.
And on most of the NSX, this is the air that we are breathing while inside the car….


So, disassembled the sensor body, cleaned it and re-adjusted the tiny gap of fan holder which required delicate touch.


Now, I can see the sensor head.

Regards,
Kaz