Hi, Sudesh.
I’ll touch on the A/C system on this particular NSX later.
Please review it before starting the evaporator service as you may need to take it out any way AND replace other parts as well.
First, about the cleaning of evaporator (evapo).
This level of debris on the evapo is nothing new to some of the NSX based in Japan.
For really dirty evapo, I normally use alloy wheel cleaner which can be used on some of the aluminium.
It dissolves even the metal brake dust so quite powerful chemical. Some people uses the industrial alkaline cleaner but I haven’t tried it in UK.
If you are careful, you can use soft brush in the horizontal movement without damaging any of the fins.
Then, wash it off with warm/hot water using garden sprayer.
I normally repeat above process two or three times before moving on to the next step.
I then spray medial alcohol or even Dettol depending on the availability.
By the end of this process, almost all of the fume is gone. Please make sure to unblock the evapo drain tube before carrying out this process. It can drain significant amount of fluid when the drain is clear so don’t be afraid to spray lots of warm/hot water to rinse off the chemical.
Now, about the A/C system on this NSX.
As there was not much info in your post, I could be wrong but you’ll need to investigate the entire A/C especially, if the compressor was not working for a while.
First, from your photo, it looked as if the evapo fin was covered in green.
Sometimes, digital image won’t show the true colour of actual object but the green colour could be the leak detector added to the A/C gas.
Your friend of A/C specialist should have UV ray light so if you apply it to the evapo and if you get fluorescent green like the photo below, I’m afraid there is no point in cleaning the evapo while it’s inside the car if the leakage was severe.
The bonded debris is actually caused by the A/C oil (not the gas) and it is very sticky material. Even you wash the evapo thoroughly and re-charge the A/C gas, it will end up in the same result if the oil leakage was severe unless you fix the leakage.
You will need to take out the evapo from the housing and then take it to the welder or if the leakage was from many places, it would be best to replace it with the new one but expensive…
The key for the healthy and long lasting A/C system is to act at the first sign of issue.
When you start hearing some noise when the compressor engages, that is the time to start looking into the possible future failure of A/C system. There is a noise because of a reason and noise is generally caused by metal touching another metal without enough lubrication.
A/C is a closed system but unfortunately, the gas and oil can leak from the O-ring used at many places around the pipes and fittingd.
So, if you lost the gas in the past, you could also lost some of the oil as well. The O-rings are specially designed for each type of gas (R12, R134a).
Please check the pipe connection points with the UV ray light if the leak detector was added to your system. The common places for the leakage on our NSX is at the compressor, the two pipes at R & L condensers and the fittings of the evapo at the firewall.
Obviously, in order to check the internal leakage at the evapo, you will need to remove the blower motor unit.
If you acted early enough, you will be fine by just replacing the compressor with the re-conditioned one and also replace the receiver that is located at the front of the radiator.
It is acting as the filter for the A/C system as well. If there was any leakages, it is best to replace the O-rings at this stage.
A while ago, I supplied the specific O-rings to one of the member together with the receiver and he seemed to be happy with the result.
Unfortunately, if the noise at the compressor was left too long (possibly, the case on this particular NSX), I’m afraid you have circulated many tiny metal debris inside the system and almost clogged the filter at the receiver.
You must replace the compressor and receiver to start with.
Then, due to the lack of maintenance and long term leakage from the O-rings, the system was no longer in closed state and thus, created internal corrosion at the fitting as well as internal wall of pipes. If the corrosion is severe, you will need to replace some of the pipes. This could be a big job for some of the pipes.
Before replacing the compressor, some people blow the pipes with compressed air to get rid of any metal residue but please be careful with handling of remaining oil as it could cause future corrosion.
For this particular NSX and if you blow the pipes as above, you will need to spend extra time during the vacuum process in order to get rid of any moisture that may enter the system through the atmosphere as well as through the compressed air.
One thing to note.
On earlier models, if you disturb the fittings/pipes at the R & L condenser, you may create new leakage even using the new O-rings.
The fittings are just too old and not possible to create air tight seal. I’m afraid if that is the case, you will need to replace the pipes and the condenser. If you have EPS, that will be a big job as the EPS rack needs to come off.
So, based on the limited information on your post, you will at least need to replace the receiver and use re-conditioned compressor plus the high possibility of taking out the leaked evapo for welding or replacement and replacing some of the O-rings…
I hope I covered most of the points.
Regards,
Kaz
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Originally Posted by Sudesh
I once sat in an NSX which smelled like cat-p*ss. Very disgusting. 
