Climate Control Capacitor Replacement

[Heineken]

It's well known that the NSX's Climate Control Unit (CCU) in the centre dash suffers (like a few other ECUs) from leaking capacitors after ~20-25 years.

Several years ago (after reading through many of Kaz' blog post at that time) I replaced the capacitors on my Climate Control Unit (CCU) before they started leaking.
One of my friends was constantly nagged that his climate control should get the same treatment and this summer I got the news that it failed ..



Due to the failure it was sure that the acid would already have done its damage by creeping under the PCB coating and attacking the copper traces.



On a first look it did not seem to be very severe but on closer inspection the damage was clearly visible. Three capacitors had discharged and contaminated their surrounding.
In two cases the affected area turned dark, in one case into a lighter colour.

A de-soldering station was used to remove all wet-type capacitors and is highly recommended for this type of work as it's quicker as well as reducing the mechanical and temperature load on the PCB.



To clean things up, the paint needs to be removed from all affected areas as the acid would otherwise continue to attack the copper up to completely dissolving tracks.



To protect the the surface and strengthen the attacked copper traces a solder coating was applied.



In addition, a small wire bridge was added to the top of the right pin for as safe contact and a bridging wire at the back of the PCB for the left pin to ensure all required electrical contact is safely restored.
The other acid-damaged areas were treated identically with one more bridging wire added. All other capacitor mounting spots were fine.



As a replacement dry-electrolyte capacitors where selected (Aluminium-Polymer and Ceramic) as far as possible.
For one capacitor (C6) no dry replacement was found so a regular but especially tough one (10.000 hrs at 125 °C) was chosen.
The parts and mounting location identifiers can be found on the Digikey ordering list: http://www.digikey.de/short/7vzzjn



Before re-installation into the car, the affected areas were treated with a clear protection coating from Kontaktchemie using a brush. Then re-assembly and back to the car for a functional test.
I won't explain the process of removing the centre console as it's readily available but the test procedure might be interesting.

Whenever you press the both round buttons on the CCU the internal fault memory is shown using the symbols on the display and the LEDs on the front buttons.
The unit needs to go through all operation modes to ensure all potential issues are detected. To do so, put the fan to "Auto" mode and slowly run from lowest to highest temperature - this process should take about one minute. Now press "AUTO" and "FAN" simultaneously (which is acknowledged by a beep).

If everything is OK, no extra LEDs or extra symbols light up. If they do, each error is encoded according to the following table:

If you forgot to attach the in-cabin temperature sensor (like I did at first ) the "MODE" symbol would be shown.
After re-attaching the sensor, turning the ignition on and off as well as repeating above process no more errors were displayed.



Of course, the self test does not guarantee that everything is fine but leaked capacitors typically cause error entries and no errors should be present after a repair.

The owner of the CCU and me are happy about the repair and hopefully the remaining future capacitor replacements are going to be done before any leakage happens.