Air Conditioning Compressor 1991 NSX

[Formula 91]

Thanks for the reply .I have checked there website and I am impressed with the prices including delivery to the UK. Do the american parts fit okay and am I better going for a new part rather than a reconditioned compressor . Also anybody any idea how many hours it takes for fitting the parts at a garage.

[lotusolly]

I replaced mine with a Denso remanufactured unit from Rockauto and had no problems.
Kaz has mentioned previously that there are a couple of different versions which vary on the load that they put on the engine. If you search on here you should be able to find his post regarding this.
The only other thing you need to bear in mind is that the pulley size is different on US spec units and you will need a different size belt,. When I next go to the car I will check the size for you and post it up. The correct size one was only about £7 from my local motor factors.

Olly

[nigel]

You can replace it with a Honda Legend compressor and switch the NSX pulley to the Legend one for a great savings and have a new Honda compressor.

Cheers
nigel

[Formula 91]

Thanks for the replies . I think I will go for the Denso Compressor as well .Anybody any idea on fitting times for the repair as it looks like it may be a nightmare to install the new part .

Ricky

[Hagasan]

If my memory serves me correctly the Denso compressor on our cars is a common part. I don't have the part no. at hand but I know it's the same one used on a Porsche 964. The differences will be the service ports the pipes connect to and the clutch/pulley. The NSX has I think two different pulleys that stick out from the body different distances.

You may be able to find a cheap Denso unit and swap over the service port and pulley assembly. Just find out the Denso part no. Google it and see what other cars it's fitted too.. Sometimes the same part can be priced with a huge variance depending on what car you buy it for!!

[Kaz-kzukNA1]

Based on your old post, I believe your NSX is 91 spec and thus, came with the R12 A/C system.
The expensive price you mentioned is probably for the PR7/PW0 R12 spec compressor that is very likely to be discontinued outside of Japan by now.

Not sure whether your A/C system is already converted to R134a, later spec or not but if your compressor has failed, just get P9K R134a spec OEM compressor (manufactured by Denso, shared with Integra, NSX, etc) or equivalent Denso remanufactured one and retro fit the R134a conversion kit.
The Denso compressor design spec is 10PA15C type so any compressor based on this has the same body shape.

From the Eng power loss and A/C efficiency point of view, R12 system is better than the R134a one so there are owners still using the R12 system on their NSX in Japan but the gas itself is getting expensive every year…..

Strictly speaking, you should replace the o-ring when converting to R134a spec from R12 but even during the NSX Refresh plan at Honda factory, they won’t replace it when doing the conversion.


I touched on A/C system on NSX Prime and NSXCB several times so please read them together with the info in this post;
http://www.nsxcb.co.uk/entry.php?1319-R12-and-R134a-A-C

http://www.nsxcb.co.uk/showthread.ph...062#post107062

http://www.nsxcb.co.uk/showthread.ph...938#post103938


You need to be aware that the diameter of the R12 spec receiver is larger than the R134a one so if you decide to use the R134a receiver on 91 model, you will need to replace the holder bracket as well or make small modification to your existing one.
The basic concept of the receiver feature is the same between the R12 and the R134a but the R134a one has better internal filtration design if you cut through and inspect it.
However, for the extra capacity and due to the bracket difference above, many 91 model owners are still using the R12 spec receiver even after converting to R134a gas.

As mentioned above and in the above links, the compressor body dimension is the same regardless of R12/R134a or even other Honda models or year models.
You just need to keep the correct combination of the A/C compressor CL/pulley and the compressor mounting bracket on the Eng block.
The bracket was changed from 97+.

If your CL/pulley on your existing compressor is fine, then just get new P9K spec compressor or re-man one and reuse the CL/pulley from your old compressor.
If you are using the aftermarket header on your 91 model, it would be good excuse to spend extra and get the 97+ mounting bracket to shift the compressor away from the header against the radiant heat.



Replacing the compressor is not too bad.
Mainly, you just need to remove the U-shaped stiffener at the bottom of the eng/gbox assy and then remove the grey front cross beam to get access to the compressor.
Honda will charge you about 2.7Hr including the discharge/charge of A/C gas.

The receiver depends on the type and what you are going to do with the receiver bracket but in general, you will be quoted 1.2Hr excluding the discharge/charge of A/C gas (already included in the compressor labour charge of 2.7Hr).


Now the biggest challenge would be the expansion valve.

There are R12 and R134a spec valve and despite the different operating pressure, R12 spec one works even after converting to the R134a gas. You should replace it if breaking the pipe connection together with the receiver.

If the fitting at the valve can be loosened without any issues, you are very lucky.

Over the years, quite often, the soft aluminium fitting is seized onto the expansion valve thread and even with the use of double wrench, if you damage the fitting (that is part of the evaporator), you will be forced to take the dashboard out (the big cabin surrounding parts in front of the driver and passenger seat) to replace the evaporator and that’s a huge task.

Because of this, in Japan, we don’t touch the expansion valve without first getting the owner’s consent that there is a high risk of damaging the evaporator fitting when replacing the expansion valve and thus, it could result in taking the dashboard out in order to replace the evaporator. Expanison valve comes with the new evaporator unit.

You can access the expansion valve by removing the blower motor fan housing under the bonnet so it will be about 2.0Hr to replace the valve if the fitting is not seized.
If you were quoted more than 6.5 – 6.9Hr, that means they are going to remove the dashboard so ask them to try the blower motor fan method first.
The Honda labour charge system only shows the procedure of replacing the expansion valve by taking the dashboard out…..

If the dashboard is coming out, you may want to replace the evaporator anyway. It’s sided (RHD, LHD) so make sure to order the correct spec if ordering the evaporator. There are reasonably priced aftermarket evaporators available for LHD NSX but not sure for the RHD onel.....

In Japan, we normally replace the whole heater unit as an assy (evaporator, heater core, control actuators, white big housing, etc) because there were several reports of coolant leakage from the heater core and good refresh of electronics drivers as well.


Kaz

[Formula 91]

Hi ,Thanks for all the replies. The parts are on the way from Rock Auto .

Ricky

[greenberet]

If you are using the aftermarket header on your 91 model, it would be good excuse to spend extra and get the 97+ mounting bracket to shift the compressor away from the header against the radiant heat.

Looking at the US parts catalog at oemacuraparts.com, it seems that the R12 compressor (part number 38810-PR7-A01) was only used in US NSXs for the 1991 and 1992 model years. It looks like the R134a compressor (part number 38810-P9K-E01) was introduced for the 1993 model year and was used until production ended in 2005.

Interestingly, the bracket that holds the compressor to the engine block was not changed in 1993 along with the compressor, but only in 1997. As of that year, both manual transmission (now 3.2 liter) and automatic transmission (still 3.0 liter) cars switched from the earlier compressor bracket (part number 38930-PR7-A00) to the later bracket (part number 38930-PR7-A01).

Since the earlier bracket was installed with the later compressor at the factory, since the later bracket was installed on both 3.0 and 3.2 liter engines, and since you can use the same belt with any combination of compressor and bracket, how exactly did the design of the bracket change? It couldn't have shifted the compressor away from the header by moving it towards the right of the car because Honda never changed the part numbers of the crankshaft pulley and tensioner. Does the new bracket shift the compressor away from the header by moving it a bit further towards the nose of the car, requiring that the tensioner be backed off slightly?