Air-Con - Evaporator Question

[wixer]

I'm just looking through Amamyama's parts listings ( as I might need to replace the evaporator over the winter ) but there's two listed for my model year NSX 1991 5MT.

Any way of knowing which one is actually correct ? Or is it a case of either will fit ?

Thanks in advance.

14319

[Kaz-kzukNA1]

-003 was superseded to -013.
It's for the R12.
OEM one comes with the exp. valve.

If going aftermarket, the evapo is sided between RHD/LHD so be careful.
While the aftermarket LHD evapo was readily available in the past, not for the RHD one unless you asked the heat exchanger company.

You could stay with the R12 spec but can use R134a one if thinking of converting the system in the future.

As a side note, check the heater core if replacing the evapo.
Some NSX showed slow coolant leakage from there.

The heater core is not only sided (RHD/LHD) but also the latest OEM aluminium one won't fit inside the big plastic heater unit/housing if your existing one is the brass spec.
With early model, unless the entire heater unit was replaced in the past, very likely that you have the brass one.
Just take it to the exhaust or welding place for the repair.
For LHD, aftermarket one is still available.


BY the way, from your winter chassis refresh thread, you are chasing the multiple a/c issues.

Already replaced the R & L condensers with new and used ones, new triple pres SW, new FCU, etc.

So far, seems to be no leak detected from the fittings so no mention of replacing the O-rings, etc.
No mention of exp. valve.

If you are getting to the point replacing the evaporator, you may want reviewing the state of the existing R12 system and consider converting it to R134a.
Iincluding the compressor, all o-rings, front end pipes, (not a must but the flex discharge/suction hoses) as you will be flushing the system.

Every time when you disturb the system and expose the drier to the atmosphere, you are recommended to replace it.


It's your decision but personally, before deciding on replacing the evaporator, I strongly recommend finding the cause of the leakage because your leakage is what I call huge one yet not being detected.
At such rate, you are losing the compressor oil quite a lot as well.....

So far you had....
Had it re-charged with RS24 by Bee Cool with no leakage detected at that time.
Lasted only 2 months with no refrigerant pressure left.

Re-visited at the end of June.
Found to be leaking from the schrader valves.
Replaced them.
After only 1 month, no more cold air blowing…..


Bee Cool has been used by many NSX owners so have enough experiences.
Lots of good feedback from owners of other makes/models.

If they can't detect such huge leakage, must be leaking from hidden places.

When the A/C was working at least for one month in July, did you see lots of water dripping on the garage floor after parking the car?

Did they add the green leak detector to your system?
If so and if leaking from the evaporator at such huge rate, you should see traces of green dye at the garage floor.

It could be leaking from the fitting of the Exp valve.
Remove the blower fan unit under the bonnet.
If leaking from there, it will not only spray the green dye but also the compressor oil.
Your evaporator would be covered in sticky greasy oil/dust/debris all over the fin.

If leaking from the evaporator, for some reason, it tends to be the lower pressure side after the exp valve. That was the case on mine as well.
You may even be able to see the bottom end of the evaporator if you can stick in the endoscope or the inspection mirror there.

If you have proper UV/dark light, point it at the exit of the drain tube under the floor just behind the left side of the steering rack.
You should be able to tell whether it was leaking or not.

The most common place for the leakage is the evaporator joint/fitting at the front bulkhead.
It will be covered in greasy sticky oil but easily detected by any a/c specialist.

Remove the centre floor channel long flat plastic cover.
I have seen several NSX with leaking from the fittings hidden behind this cover.
Some even had small cut to the pipes.

Look for the fitting at the R & L condensers.
One of the most popular place for the leakage.

Look for the compressor housing plate.
On many early model NSX, saw oil leaking from the plate.

If doing DIY, you may want consider getting at least the manifold gauge and the vacuum pump and leave the system under vacuum overnight for the leak detection.
That's what I normally do after the A/C Refresh.

Replacing the schrader valve is a must for A/C Refresh.


Kaz

[wixer]

Thanks for taking the time to reply Kaz. Yes, I've still yet to get to the bottom of the air-con issue. The reason for putting the post up, is because I'm ordering some parts from Amayama so am considering adding the evaporator unit to the list. I'm including all the seals for the entire system, although I've put new ones in the front pipes & have a new condenser fitted, so other than the compressor & evaporator the main larger parts of the air-con have been replaced.

Weirdly, I have had no leaks on the garage floor & have ran my hand around the carpet next to the Hevac unit but didn't find any dampness. I've looked around the front end & the engine bay but no signs of any leakage. I think Bee Cool added the green dye but I'm suspicious they didn't on the second re-charge, having not yet found any sign of it. I was driving the car when the temperature started to increase, so I did look when I got home, to look for signs of leakage but nothing visible. I did intend to get the car to them again for a leakage check but time ran out & I've now SORN'd the car for a driveshaft & clutch replacement over the winter. Maybe I'll find signs of a leakage when I remove the underfloor tunnel covers. I'll look into a DIY kit to see if I can do a pressure check myself.

Cheers