air conditioning pump

[britlude]

as i seem to be going through my NSX at the moment, another thing on the list of tweaks is the air con pump... it's sometimes noisy, other times fine, so time to replace (as it needs a gas top up too, thought it the best time!)

mines a JDM 1992, was running R12 before it was replaced a few years ago..... now i know the dryer has a different thread to it's connectors, just to be awkward, but is there any differences to the pump plumbing connections?

i know the advice is to go for a 38810-P9K-E01 spec pump, is that the denso 471-1174?? (just checking before i order one!)

ta muchly!


edit... found this thread http://www.nsxcb.co.uk/showthread.php?12838-Air-Conditioning-Compressor-1991-NSX basically all the same body design, might have to swap my pully and porting onto it..... or the later bracket...

edit 2... from a -pk9 search on rock auto.... https://www.rockauto.com/en/partsear...um=38810P9KE01
DENSO 4711193.... 140mm pulley
DENSO 4711194.... 125mm pulley
DENSO 4711174.... 125mm pulley

[goldnsx]

Dryer: same threads between R12 and R134a version. R134a is the way to go. R134a is smaller, you need the smaller bracket from Honda for a perfect fit.

Compressor: I went with the 93 version of Honda, I've just took over the top plate from the old one to attach the old hoses. You have to do that if you don't change to 134a-hoses as well (not needed).

Adjust the oil in the compressor. A new one comes with the full amount for the complete system usually 150 ml. The NSX has 120-140 ml distributed over all components of the A/C. Oil is hydroscopic, don't let the system open for hours.

Better replace the clutch and the stator with new compontents. There are changes in 1997 (the new headers need more space) I've heard of, Kaz knows more of it.

I've no idea what aftermarket part fits. In the US they've got an unit with a smaller pulley (Integra) and swapped that out. But as the clutch is built in the pulley it doesn't really make sense. After 100k miles my A/C clutch was completely gone...

[NSXGB]

The P9K compressor I got from RA had the 140mm pulley. I can confirm the part number over the weekend if you like. Unfortunately my order history only goes back 2 years. You should be able to re-use your belts too.
I got the later bracket but the company that fitted it said that there was no difference - I take that with a pinch of salt - I think there may be a millimeter or so different... YMMV.


EDIT: Definitely was the 4711193 compressor.

[Kaz-kzukNA1]

Dryer: as per goldnsx's comment.

Strictly speaking, the filtering method is better with OEM R134a dryer over the original R12 one and the moisture absorbing chemical is specific for R134a so best using OEM R134a dryer.

However, if you want, you can use OEM R12 dryer even with R134a refrigerant.

Many owners in Japan that originally had R12 from the factory are using R12 dryer on R134a system in order to keep the extra safety margin on the capacity (classic dryer is acting as accumulator as well) in case of overfill as well as to keep the original bracket. OEM R12 dryer has larger diameter/capacity over the R134a one.

The silica gel used in the aftermarket dryers are most likely compatible with both the R12 and R134a so just one spec for both.


Compressor: The service port (the cover on the comp. where the flex hoses are connected) is different between the R12 and R134a spec but it doesn't come with the Denso remanufactured one any way so you will be forced to transfer your existing one to the new comp..

I don't know the reman comp. comes with a new gasket but not expensive so just get new OEM R134a spec or if you get aftermarket one, the material is very likely to be compatible for both the R12 and the R134a refrigerant/oil.
[Update 14/Jul/18: Denso re-man compressor does come with a new gasket inside the box.]


For the Denso reman. comp., you can forget about the 471-1424.
It's for the R12 system.

Based on the direct information from other owners who bought 471-1193 and 471-1194, I recommend 471-1193 for pre-97+ NSX.

Both are for R134a but -1193 has similar pulley diameter as the OEM one.
You don't want spinning the comp., faster than how it was tested.
Also, saves the time searching for a different ac belt.

From what I heard, both -1193 and -1194 don't have the correct offset at the CL/pulley for 97+ mounting bracket.
[Update 14/Jul/18: Denso 471-1193 does have the same pulley diameter as the OEM one but CL/pulley offset is only suitable for 97+ bracket.
If installing on pre-97 models, you need either swap the CL/pulley assy with your existing one or replace the mounting bracket with the 97+ spec.]

Therefore, if you own 97+ models or swapped the bracket to the later spec, you will need to use your existing OEM CL/pulley to get the correct alignment or find alternative solution (like the owner, flyingsniffer below) if you want keeping the comp. away from the header.
[Update 14/Jul/18: Denso 471-1193 does have the correct offset for 97+ models. No need to change anything if installed on the 97+ models.]
I know at least one owner is driving with 471-1193 for his pre-97+ model for quite some time.
He is using the new CL/pulley came with the reman. comp..
[Update 14/Jul/18: I better double check with this owner because unless he is using the 97+ offset bracket, the alignment among the 3 pulleys (crank, idle, compressor) won't be correct.]
That's one of the benefit of using the reman. comp. over the OEM one.
OEM is more expensive but does not come with the new CL/pulley.
You need to buy it separately.

Our member flyingsniffer reported here that he bought 471-1194 for his 97+ model but encountered with the offset and smaller diameter issues.
He got used comp. from Toyota Avensis 1.8 petrol (98-00) off ebay and just transferred the CL/pulley from it onto his newly acquired 471-1194.
He now has correct offset and simialr diameter for the 97+ models.



I'll be doing A/C Refresh for another owner soon so hoping to receive all the parts from Japan, US including 471-1193 in the near future.
(Thank you to one of the owner here who measured the actual CL/pulley diameter of 471-1193 for me just recently.)



As a side note, if replacing the comp. and if it was already making noise, you may want replacing the Exp valve and have your system flushed before installation.

After removing the existing comp., please check the colour of the oil and measure the amount left inside.
If you see lots of metal flake, dark brown oil colour, lost so much oil, etc, you must flush the system.


If it was not flushed before the R134a conversion, you still have old mineral oil in the system so another reason to flush.
Can be left as mineral oil can't circulate with R134a refrigerant and sits there forever but it just another impurities.


New reman. comp., is pre-filled with the specified oil with correct total system amount (min: 160cc, max: 180cc, including the amount that will normally sits at the low section of the pipe, evaporator, condenser, dryer) so if the system is thoroughly flushed, please do not drain it.
Never drain more than 50cc.


Too much oil will reduce the efficiency resulting in poor performance but you have 20cc to play with so plenty margin.


Kaz

[goldnsx]

By flush do you mean the simple standard procedure of the A/C service station or flushing every single line/component?

Too much oil raises the system pressure. So it's a good idea to check them according to the service manual after you've refilled the system.

[britlude]

thanks for your input... looks like a 471-1193 it is then.....



...oh and i had to google YMMV!!!!!


edit.... ordered from Rockauto, with dryer and expansion valve.... £207 all duties and post paid!

[duncan]

Honda Service Bulletin advising differences between R12 and R134a systems.
r-134a-refrigerant-ac-systemb92-027.pdf

[NSXGB]

No probs. So handy paying the duty up front with Rock auto.
Still a great price even though the exchange rate is poo for us.

thanks for your input... looks like a 471-1193 it is then.....



...oh and i had to google YMMV!!!!!


edit.... ordered from Rockauto, with dryer and expansion valve.... £207 all duties and post paid!

[britlude]

received the pump and bits from Rockauto,
IMG_20180713_105605 by jon sutherland, on Flickr

i had some time to check the car today.... i was going to change the sump gasket, but as a lot of parts are going to have to be removed to do the sump gasket (as headers have to be removed) i shall combine AC pump and sump gasket later in the year!

anyway.... the new pump.... pulley to centre of mounting boss....
IMG_20180713_111846 by jon sutherland, on Flickr

and the pump on my '92 car....
IMG_20180713_111919 by jon sutherland, on Flickr

new pump approx 47/48mm, old pump around 55mm

[britlude]

if you compare the pulley to the mounting AC unit case bolt, the new unit is pretty much flush

IMG_20180713_105542 by jon sutherland, on Flickr

and the old unit has the difference as expected...
IMG_20180713_112017 by jon sutherland, on Flickr

so the pulley is closer to the body of the AC, meaning the AC pump will have to move outboard approx 6mm to take up the difference, and moving the AC pump away from the exhaust down pipe.... so appears to be for the later style AC mount....

now the choice is to try and find a late model AC mounting bracket (that is definitely a later model as listings i've seen seem to have them listed the same for the whole production period!) or swap the pulleys over.... not the straight bolt in swap i had hoped for!!!