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R12 air conditioner

1 January 2021
dear All,
My NSX is actually in CC Honda for the timing belt.
Further to this intervention, I ask them have a look at the AC (which doesn't blow cold); the car was not drive during last 10 years.
They told me that it was R12 gas (which is now forbidden in France).
so they told me no possibility to fill the climatisation (and there were no modification of the original system).
I remember (and i am pretty sur) this topic is a usual topic and solutions exist.
I think there are 2 options: filling with old R12 gas stock or modifications for new gas.
what did you do?
Is there a specific kit selling by Honda or other (not expensive)?
so, only need to change the oil, empty R12 gas in the system, change the R12 by R134a adaptater?
If going with R134a a, yes.

If the A/C wasn't running for 10 years you might better change all o-rings, receiver.
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many thanks goldNSX,
as far as i understood, it seems very easy. my cc Honda in France explain that it is very difficult to upgrade; change all parts...I think he doesn't want to search.
many thanks goldNSX,
as far as i understood, it seems very easy. my cc Honda in France explain that it is very difficult to upgrade; change all parts...I think he doesn't want to search.
Maybe or he has no clue about it.

Not so sure about the system if it has been running for 10 years. I wouldn't trust the compressor. Has the CCU ever been revised. Most people wait until it shows signs of failure but the longer they wait the less possible is a repair. Depends on how important a working A/C is for you and how much money you can dump into it.
Either the system is OK or it is STUFFED.

The cost of a generic retrofit kit should about $50. The cost of gauges and a vacuum pump is $160 (Amazon). It is easy to become a Certified YouTube Expert, as there are several good MVAC occupational licensing videos to choose from.

ASSUME system is OK because the penalty of failure is $50, TWO hours, and difficult to appreciably further degrade the system. Go through the process of (vacuuming the system out [if empty] and) charging with oil + refrigerant. This should take a couple of hours, which is the time to take a car to a shop and have them work on it; so again low penalty for failure.

If the system is STUFFED, you are in a world of hurt. Your tech does not want the job because it could be thousands of dollars to deal with and he [rightfully] doesn't even want to touch the system.

Report back.

Remember: maintenance on the NSX is cheap, repairs are expensive.

EDIT: OP has replaced the CCU board with a new unit.
If the system still has residual R12: It's not advised to mix R12 with R134a at the same time, but it WILL work just fine. The upside is a working system, delay expensive repairs, and the downside is a possible regulatory violation in the EU.
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I agree with you in most points. Been there, thought about that but I still go to my trusted A/C mechanic. Things run a little bit different in Europe than anywhere else.

My A/C guy has an A/C station where you have full control over every step without the hassle of dealing with 1000x tools, also the amount of oil sucked out and amount to be refilled. After refilling you just start the engine, active A/C and watch the gauges on the A/C station.

Your service guy won't be happy to suck the R12 out as it's very ancient. :)

Changing all A/C parts in Europe can easily put you in the EUR 10'000 range with European part prices. :D

For the oil bottle of the retrofit kit the A/C guy needs an oil injector. If your system is loosing pressure due to a leak (there WILL be several leaks after 30 years and 10 years not running, believe me), it's a wild guess how much oil has to be added later again. So better do the best possible and change all the accessible rubber parts DIY before doing anything else.

Last but not least: insist on PAG46 oil if your A/C guy normally uses a 'all-for-one' oil.
There are R-134a refill cans that are pre-charged with R12 compatible oil (see the original Interdynamics YT video in above link).

I do not know the availability of such in the EU. An oil injector and flushing tank isn't expensive but requires a compressor, and the pile of required tools begins. (And then you get a six-car garage, shop with an attached house like I have).

However, once the OP sees the cost of repairs and shop time: the cost of tools will be a rounding error.

As for the mixed R12, The EU should have a Carbon Credit program to destroy R12 for a cash bonus.
There are R-134a refill cans that are pre-charged with R12 compatible oil.
No chance to get them in the EU, maybe in Lithunia where our friend Tamoske is. :D:D:D

The retrofit kit oil is basically PAG46 with some additives to protect the o-ring from being eaten up by the oil. It's a band-aid and quick and dirty solution that works but for how long. The A/C seals of a Denso compressor are already compatible to both oils but I guess that will fail first after 30 years of use/non-use. A juice of dye with the first filling would be recommended.
In Europe, top-up or re-charging the system with the R12 is prohibited.
Existing A/C system with R12 is allowed to keep operating.

If not in operation for 10 years, big question mark on the state of your A/C system and that will become the main deciding factor for your option.

From what you wrote so far, please take your NSX to the A/C specialist.

As you won't be doing DIY, I will leave the detail and won't list all the parts that should be replaced at the time of service.

1. Use refrigerant R426A (sold under the name as RS24 or R24)
Drop-in substitute for the R12 so you can keep re-using the existing R12 hardware.
No need retrofitting/converting to R134a.

The cheapest option if your existing system is healthy and maintained well.
Same goes if it can be repaired at the minimum cost.

Otherwise, you may want considering other options.

Several UK owners went with this option and happily running their A/C system.

2. Retrofit/convert to R134a - basic spec
Saving the initial cost of retrofit/conversion.
Only good if your existing R12 system is healthy or at minimum leak (not re-charging every year or two).
Re-use existing R12 compressor presuming it's not making grinding noise.
Requires charge port adaptor and ND-OIL8 or suitable PAG/POE oil for your compressor spec but these are very likely to be included in the retrofit kit.
Replace the drier/receiver.

3. Retrofit/convert to R134a - pricey spec
Addition to the above basic spec, replace compressor to the R134a spec.
Carry out preventative service such as replacing majority of the o-ring to R134a spec, flushing the entire system, etc, etc, etc…..
The limit would be how much you are willing to pay especially for the labour.

Didn't know the basic retrofit to r134a is so simple. I don't think refrigerant R426A is available in United States for non-licensed consumers? What would happen mixing r12 and r134a?
Kaz has given the correct keyed answer. 100%.

The US EPA takes a dim view of blending R12.

Working with refrigerants can be dangerous and can cause severe burns. Getting a shot of refrigerant in one's eyes can cause permanent blindness. Use gloves, glasses, and use safety equipment!

Now for a purely academic discussion for informational purposes only:

R12 systems use mineral oil. R134a cannot move mineral oil. POE/Ester/Polyester is a compatible oil to R134a and R12 mineral oil. A system without oil moving around will have catastrophic consequences.

There are blends (such as Freeze12, available on eBay now and require no license) that can be used with R12 without too much issue. I, and others, have used these blends without much issue on the NSX, but they have to be monitored. I daily drove my previous NSX for 15+ years in Sunny California, replaced my own evaporator, but I also have an MVAC license. It should be emphasized that blends are not advised. From memory Freeze12 is mostly R134a with other gases that CAN move mineral oil...but those gases tend to leak out first.

An A/C system requires oil to be lubricated or it will grenade and you will be in a world of pain. Flushing the NSX system of debris is a monumental task that requires at least 20-30 hours, removal of the interior, very close quarters, and painstakingly detailed work...especially at the evaporator and expansion valve. Few people will want the job at any price....so it is usually a DIY or the authorization of a very expensive estimate.

Migrating a working R12 system to R134a can be a simple matter of adding the R134a fittings, POE/Ester oil , and proper charge of R134a. The seasoned o-rings tend to seal R134a despite being a much smaller molecule. Use all safety precautions.

I generally assume the NSX system is working, because if there are any problems (such as "The Black Death" of debris inside the system) it is going to be A Project. And there are little downsides of assuming a system is working because one really can't make it any worse by attempting a R134a retrofit and the cost of consumables is less than US$50. Note: Injecting oil requires a flush tank (US$30) and an air compressor.

A preliminary check for Black Death on a discharged system can be done, clean around the compressor, remove one of the compressor fittings, and use a white cloth to wipe the inside of one of the compressor pipes. If you see grey-black particulate residue: that is an indicator of a failed system. Personally, I would still convert to R134a and hope for the best, because there isn't much to lose.

Decision Tree:
Discharged/Empty: Do R134a conversion with a new receiver dryer

Low Charge: decide on topping off with R12, a blend, or a R134a conversion. If R134 conversion, go to Discharged/Empty, and a receiver dryer is optional, but recommended.

Blocked/Debris: disassemble, flush everything, new: o-rings, new compressor, new expansion valve, receiver dryer, and go to Discharged/Empty. Alternatively, consider your car to be functionally one step closer to the NSX-R spec: no a/c.

Becoming a Certified YouTube Expert has never been easier, often takes less than an hour, and there are a lot of amazing people out there sharing their knowledge; take advantage of it.
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Thanks for the explanation. What causes the 'black death' and what are the symptoms?

I did a DIY AC overhaul a few years ago; the below is from memory but I think it's accurate.

If the compressor runs low on oil or the oil becomes degraded internal friction will begin to wear away the teflon coating from the pistons and other moving parts inside the compressor. This mix of metal, teflon, degraded oil, and refrigerant then circulates throughout the rest of the system and is called "black death."

Unless this "black death" is flushed from the entire system there is a chance that it will recirculate back to the new compressor and destroy it. It also might block flow through the small passages in the condensers, leading to lower system efficiency.

Flushing on the NSX AC system can be difficult because the front condensers shouldn't be disconnected due to the possibility the aluminum connections will be destroyed from corrosion.

If you need to replace the compressor I would recommend to replace the evaporator in the dashboard (and of course the receiver/drier) at the same time. Yes, this is much, much more expensive but it's still better than doing the same job in two parts and having to open the system twice.

Good luck to OP!
Hi everybody, I find someone close to Paris which fullfil the AC with R12A gas. Just to knowledge, is there a specific thing to do after refilling? The compressor seems to works fine and no leaks (no trace of leaking with the yellow tracer) but no very cold air in the cabin... Is there something to reboot? or to adjust?
Nothing to reboot. Make sure they check the pressures and temperatures after refilling to make sure the system is functioning well. There may be other issues with the HVAC system (high/low pressure switch, etc.)

If the system was low on refrigerant then you have a leak some place. It might be a small one but you'll want to keep an eye on it to figure out where.

The dye test is good for testing parts of the system that you can see. There is another test that samples the air to find a leak-you might have to use one of these to check other parts of the system like the evaporator.
Hi everybody, I find someone close to Paris which fullfil the AC with R12A gas. Just to knowledge, is there a specific thing to do after refilling? The compressor seems to works fine and no leaks (no trace of leaking with the yellow tracer) but no very cold air in the cabin... Is there something to reboot? or to adjust?
What is the air exit temp at the center vents while running the A/C in 'fresh air mode'?
What procedure did your technician perform?
-- vacuum system
-- weight of R12 added
-- pressure of high and low ports

Things you can do:
1. verify the compressor engages (center spins, clicks on/off)
2. is the piping hot or cold under the hood (only check the engine area when engine is off)
3. does the heater work? does the water heater valve operate: turn off/on
4. with a voltmeter, test the triple pressure switch
thanks all! after a 100 kms trip back and a night of sleep, I just have a trip with my NSX. Today in France it is sunny and 26 ° outside and ...Miracle!! the AC works!! 18° in the car (I didn't have exactly the temperature but the air is cold). Thanks very much for your help and your time