Climate Control Issues

[Sudesh]

I know most have read the CC issues and Kaz's service on the boards.

I'm having a CC issue and not convinced yet its the board, I inspected it myself and its looks brand new, not a single sign of damage or capacitor leakage anywhere.

The symptoms I'm having are all related to the fan speed and on/off.

The fan speed works, but when its down at its lowest point it still blows as if its on the first 3 clicks, then when I put it below the first line where it's at it lowest speed [almost sounds off] the fan still blows as if on the 3rd click, also when I press the off button the fan still blows and doesnt shut off UNLESS the knob is turned all the way up to the faster speeds and then when I press off it works??

So after doing some testing today, I found a relay under the bonnet that was dead, I replaced that and the CC worked perfect for a short while, but then it went back to the symptoms I mentioned above, checked the relay, it was fine.

So I'm wondering is there more to this? Even though the CC board looks perfect could it still be the problem? Or are there more relays somewhere that I cant see? I have checked all the ones I can find and they are fine. Also ran the Diagnostics and no problems showing.

So not sure what to do from here, already spoke to Kaz about servicing the board but before I do that I was wondering does anyone have a spare CC unit or just the board so that I could test it in my car to see if it works any better, least that way I can narrow it down pretty quickly.

[Sudesh]

Heres a pic of the relay that was done, you can see it started melting at the pin. After seeing that I inspected all the relays in the car to make sure they were ok. No harm in having a quick look.

[NSXGB]

Is it from your car or a customers car?
If it's from a customers car, you could try the CCU in yours. If it does the same you will know it's the CCU and nothing else. I appreciate you may not want to try this though if it's possible the melted relay is a result of the CCU being bad.
My money is on the CCU being bad.

[Sudesh]

Its my own car Simon, been like that for a while now just never got round to doing anything about it as its not driven much so always put it off.

I wouldnt swap the CCU from a customers car unless I got permission first, probably wouldnt have been a problem but when working on the other cars the last thing I thought about was my own car, and to be honest I wasnt overly bothered about the function of the CCU on mine till now. As I have some spare time and working on some other bits, I thought I would get to the bottom of the CCU problem.

Your probably right on the CCU being bad, I just cant see any signs of it? The board looks spotless on my car and I cant see any signs of damage. Unless some of the capacitors are damaged internally and have not reached the surface of the board? I'll take some High res pics to show.




Is it from your car or a customers car?
If it's from a customers car, you could try the CCU in yours. If it does the same you will know it's the CCU and nothing else. I appreciate you may not want to try this though if it's possible the melted relay is a result of the CCU being bad.
My money is on the CCU being bad.

[Sudesh]

Pics of my CCU

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0733.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0736.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0737.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0738.jpg

[Sudesh]

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0739.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0740.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0741.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0742.jpg

[Sudesh]

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0743.jpg
http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0744.jpg

[Sudesh]

I take it no one has a spare CCU then?

[Kaz-kzukNA1]

Hi, Sudesh.

Could you show me the exact location of the relay that failed under the bonnet? I would like to know which relay failed on the A/C system.

Looking at your board, the capacitors are covered in brown sleeve and not in black.
Based on the information you provided me the other day through email, I think your board was replaced by the previous owner or someone worked on your board in the past. If I remember correctly, the latest spec brown caps were not in use for your JDM NSX year model.

While it is possible that you may have CCU issue, I think you have more serious condition outside of CCU.

The relay that you showed in your earlier post is the Denso 4P power relay and it is at high current rating with protection by the fuse. This relay is being used on many circuits and some of them are controled by the CCU.

However, CCU is controlling the coil side of the relay which requires almost no current and the pin that melted on your relay is on the power side which should be protected by the fuse.

So, I'm interested to know which relay got damaged.

Regards,
Kaz

[Sudesh]

Hi Kaz,

I dont have a pic, but if standing at the front of the car, its the the relay box in the middle, and it was the second relay in at the top from the left, it seems to be the one that controlled the highest level of air flow when you turn the knob all the way up.

[NSXGB]

Hi Kaz,

I dont have a pic,

I have trouble believing that. :):rolleyes:

[Sudesh]

lol! I wasnt near the car then so couldnt take a photo.


I have trouble believing that. :):rolleyes:

[Sudesh]

I have managed to pin point the problem with my Climate Control. As mentioned earlier I was pretty sure it wasnt the board as there is absolutely no signs of damage or leakage anywhere, and after speaking with Kaz it would seem that my board had already been replaced and upgraded to the later spec version which was a nice wee bonus to find out as the boards new from Honda UK are £1,154.97

So with some more testing I checked the fan control unit which is behind the rear bulk head lining, I tested the unit and couldnt see any faults there either. So Kaz had mentioned about the power transistor which is located on the blower unit under the bonnet.

After a quick check it was pretty clear that this is where the problem was. Before I even unscrewed it, I moved the cable back and forth and low and behold, if I pushed the cable one way the climate control was perfect and if I moved it another direction the climate control went back to having the issues. So either the transistor is faulty or there is a problem with the cable not being connected/seated correctly at the transistor end.

I havent got round to removing it yet as its very tight to work where it is and I may have to remove the blower unit, either that or I could drain the coolant system and remove a small pipe that will also give me access.

I didnt take any pics yet, But using the pic below I have indicated where the transistor is located.

[NSX 2000]

I have trouble believing that. :):rolleyes:


lol! I wasnt near the car then so couldnt take a photo.

ROFL :laugh:

Even though I might be having a s h 1 t day or there is doom and gloom evrey where, evrey now and then a read a post on here and things don't seem to be so bad :pleased:

[Kaz-kzukNA1]

Hi, Sudesh. Glad you managed to find the issue.
That Power Transistor is another common failure parts and I just hope it is just the wiring issue and not the transistor itself for your case.

It's quite expensive even in Japan or US and if you go down the HUK route, it will be about GBP268+VAT just for that small parts....

Regards,
Kaz

[Sudesh]

Hi Kaz,

Yeah already priced the part with Honda yesterday just to see what it would be. So if the transistor is damaged then I guess I'll be buying a new one.


On another note, when I replaced my relay, I priced them with Honda

Part Number: 39794-SE0-003 £26.32 each
Ebay was £15.00 each

Went to my local breaker and got them for £5.00 each, so I bought a good few lol

The relay is shared with many other Honda models

[Sudesh]

Decided to remove the blower to get access to the transistor

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0805.jpg

The transistor is located at the side of the blower at the end of the black lead

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0806.jpg

I had had already removed 2 screws from the front, then removed 2 from the rear and the transistor was free

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0807.jpg

[Sudesh]

The wiring for the transistor is sealed in a hard wax type sealant, so I didnt want to damage any of that. I noticed the transistor was very dirty and had a white build up on it, so I decided to use some light sand paper and clean it up, finishing off by using contact cleaner.

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0808.jpg

The little sensor in the middle was slightly loose so I remove the screws, removed the sensor and clean that up also, replaced the screws and installed everything back in the car.

http://i77.photobucket.com/albums/j77/icongroup/NSXPARTS/SAM_0809.jpg

[Sudesh]

After doing the above and then spent allot of the day testing the climate control, it would appear that all is now working perfect! So I'm well please. I also gave the blower a good cleaning out, wasnt too bad and had light build up inside.

[Nick Graves]

It's amazing what trouble a high resistance can cause!

If the capacitor won't fire the motor to overcome its back EMF, I assume the motor just draws too much current & overloads the relay & endangers the PCB.

If that power capacitor does blow, can you not obtain a direct replacement from Maplin or wherever & solder it into the harness & heat sink? They're usually standard items IIRC.

[TheSebringOne]

Sudesh, another great write up and another successful job well done. :)

[Sudesh]

Many Thanks! Been testing it again today under different loads with engine on and off etc, and so far its working perfect!


Sudesh, another great write up and another successful job well done. :)

[AR]

Sudesh is that an NA2 front compartment or have you updated some of the bits on yours? ABS and Master cylinder look very shiny. :)

[Sudesh]

NA2 front Ary, was just trying find a decent pic to show the location of the transistor, my master cylinder is just as shiny lol. Pity about the dated ABS though, was thinking of removing it at one stage but never got round to doing anything, so its still there.


Sudesh is that an NA2 front compartment or have you updated some of the bits on yours? ABS and Master cylinder look very shiny. :)

[eclipse1501]

A brilliant detailed post which might also help me out with a similar CC issue.