A/C receiver difference between R12 and R134a?

[goldNSX]

Is there really a difference? The part no. are: 80351-SL0-A01 (R12) versus 80351-SL0-305 (R134a). The price is also. I've basically a R12-A/C filled with R134a.

If I open the system for changing all o-rings, doing the retrofit stuff (new oil in the R12-compressor) do I have to change the receiver?

 

[carmar]

Is there really a difference? The part no. are: 80351-SL0-A01 (R12) versus 80351-SL0-305 (R134a). The price is also. I've basically a R12-A/C filled with R134a.

If I open the system for changing all o-rings, doing the retrofit stuff (new oil in the R12-compressor) do I have to change the receiver?

I don't think there is any difference. I just replace my receiver while doing the evaporator. I ordered the R12 one, although I am retrofit my A/C system to R134a. It works great.

Since your compressor is still working, I don't think there is a need for changing the receiver unless you want to retrofit to R134A.

 

[davidf]

Change it. This will prevent you from starting a new "Whats wrong with my AC" thread. :wink:

 

[Daedalus]

I agree with changing it. First off, you should anyway, since you're opening up the system. It's part of the maintenance routine for AC systems. Secondly, the desicants may be different, which would explain the differing part numbers. As I recall older R12 receivers had a desicant that cannot be used with R-134a/oil, but if it was manufactured more recently (1993 was the changeover year), the desicant should be compatible with both. Either reason is enough to replace it IMO.

 

[goldNSX]

Thanks for your responses.

I'll go with the R134a-Drier as the system will be several days open.

Two very dumb questions:

1. What is the PAG oil for in the retrofit kit? The manual says it goes into the system. The compressor has its own oil reservoir, right? I thought it goes in there. Right or wrong?

2. What is the correct oil filling while recharging with 850 grams R134a? 20 grams (cc)?

 

[swerve2007]

i am no expert but from what i understand the r134 is 'drier' than r12 so when converting you must use a lubricant additive to protect the seals. it is common to loose efficiency when converting to r134 but with nsx's small cabin size and 'full size' ac system it is not noticeable in our cars.
there are products available that replace r12 without the need of converting to r134 but ask experts what to get if you are interested.

 

[Briank]

1. What is the PAG oil for in the retrofit kit? The manual says it goes into the system. The compressor has its own oil reservoir, right? I thought it goes in there. Right or wrong?

The compressor is lubricated by the oil that is in with the freon. The compressor has no oil reservoir. Most people and even service shops will keep adding freon to a leaking system and never add oil to replace what leaves with the freon resulting is a sezed compressor.

 

[goldNSX]

The compressor has no oil reservoir.

According to the SM on page 22-82 the compressor has some kind of an oil reservoir where it says: 'Don't let any compressor oil run out' while dismounting the relief valve. So I'm a bit confused about the oil amounts in the A/C system.

I've seen on a list that the A/C of an 93-02 NSX has 30 oz. of freon and 5.0 oz/850 gr of PAG. I can't remember that anybody ever put 5.0 oz/140 gr of PAG in the system during a complete recharging. And I had to recharge quite a lot in the past 8 years due to a leak which finally be fixed next month (with all o-rings). It was somewhat like 20 grams. Maybe they did an error but if not where is the rest of the oil: A/C compressor, no?
I've searched the internet up and down and one guy said that for the Honda conversion kit the compressor has to go out, drained of the old mineral oil and filled with PAG. The retrofit service bulletin says just to put the whole bottle in the system (it didn't say compressor).

Did I confuse you definitely?

 

[Daedalus]

According to the SM on page 22-82 the compressor has some kind of an oil reservoir where it says: 'Don't let any compressor oil run out' while dismounting the relief valve. So I'm a bit confused about the oil amounts in the A/C system.

I've seen on a list that the A/C of an 93-02 NSX has 30 oz. of freon and 5.0 oz/850 gr of PAG. I can't remember that anybody ever put 5.0 oz/140 gr of PAG in the system during a complete recharging. And I had to recharge quite a lot in the past 8 years due to a leak which finally be fixed next month (with all o-rings). It was somewhat like 20 grams. Maybe they did an error but if not where is the rest of the oil: A/C compressor, no?
I've searched the internet up and down and one guy said that for the Honda conversion kit the compressor has to go out, drained of the old mineral oil and filled with PAG. The retrofit service bulletin says just to put the whole bottle in the system (it didn't say compressor).

Did I confuse you definitely?

The oil will distribute itself throughout the system; some in the compressor, some in the receiver, evaporator, condenser, etc.

First off, the mineral oil should be removed as much as possible from the system. It is not miscible with R-134a, meaning it will stay a liquid and not combine. If you're lucky it'll just sit at the bottom of the receiver or the condenser and only take up space.

Secondly, you've hit upon one of the biggest challenges with servicing A/C systems--knowing how much oil to add back. Recovery machines will have a graduated container to drain any oil removed, so it can be measured and replaced. The bigger problem is when a leak is present, you never really know how much oil has left the system. The only way to be absolutely certain you get the right amount of oil back in is to flush all flushable parts clean of oil, and put in what it requires.

 

[goldNSX]

It is not miscible with R-134a, meaning it will stay a liquid and not combine.

Some say that a chemical reaction can harm the A/C very badly as R134a reacts with mineral oil in some way.

The bigger problem is when a leak is present, you never really know how much oil has left the system.

My system was completely empty the last time I recharged it. I have a visible leak I've already located and want to repair it. How about freon diffuses over time through the hoses? Does the oil still stay in?

I'll repair my leak (all o-rings), new receiver, retrofit kit but overhaul the compressor just in the way that I change the relief valve to a R134a one.
Is it this way correct? Take the compressor out, drain the oil, fill up with PAG, flush the lines and install new o-rings and a new receiver and adding the oil to the system up to 5.0 oz. minus what the compressor consumed and recharge with 60 minutes vaccum? Right or wrong?

 

[carmar]

Some say that a chemical reaction can harm the A/C very badly as R134a reacts with mineral oil in some way.



My system was completely empty the last time I recharged it. I have a visible leak I've already located and want to repair it. How about freon diffuses over time through the hoses? Does the oil still stay in?

I'll repair my leak (all o-rings), new receiver, retrofit kit but overhaul the compressor just in the way that I change the relief valve to a R134a one.
Is it this way correct? Take the compressor out, drain the oil, fill up with PAG, flush the lines and install new o-rings and a new receiver and adding the oil to the system up to 5.0 oz. minus what the compressor consumed and recharge with 60 minutes vaccum? Right or wrong?

I replaced mine with the new compressor and it does come with oil ready, so I don't know the exact oil amount in the compressor. But you can drain your oil from the compressor and measure the amount then fill it with the same the amount with PAG oil.

In my case, I replaced compressor, receiver, evarporator, expansion valve plus flushing out the full system and replacing all the o rings. I had to vaccum the system for 2 hours and recharge 4 oz of PAG oil plus 36 oz of 134A freon (3 cans). It has been working fine for me. Hope this helps.

 

[Daedalus]

Some say that a chemical reaction can harm the A/C very badly as R134a reacts with mineral oil in some way.

That would be the "black death" syndrome. It's actually a reaction with chlorine in the mineral oil that may have been absorbed and leftover from the old R-12. It breaks down the oils used with R-134a, reducing lubrication. There's a lot of debate on this. It does happen, but it doesn't seem prevalent.

My system was completely empty the last time I recharged it. I have a visible leak I've already located and want to repair it. How about freon diffuses over time through the hoses? Does the oil still stay in?

Typically yes. The gas permeates much better than the oil does. An AC oil leak looks like any other. The oil leaves a residue and it gets dirty/grimy.

I'll repair my leak (all o-rings), new receiver, retrofit kit but overhaul the compressor just in the way that I change the relief valve to a R134a one.
Is it this way correct? Take the compressor out, drain the oil, fill up with PAG, flush the lines and install new o-rings and a new receiver and adding the oil to the system up to 5.0 oz. minus what the compressor consumed and recharge with 60 minutes vaccum? Right or wrong?

Sounds fairly thorough. How will you flush the lines? Make sure you turn the compressor by hand a few times before starting the engine.

 

[goldNSX]

How will you flush the lines?

Good question.
I've read about three types of flushing, 1st with 134a (won't help I think), 2nd with a solvent for that purpose (will do the job) or 3rd with nitrogen. 4rd one owner mentioned brake cleaner and air, mmmh, ok.

Flushing with a solvent was advised to be made to each component except for the compressor or the dryer.

Dumb question: I'm letting it recharge at a shop but how to flush as a DIY? I don't intend to bring the car for repair to them. Hopeless?

 

[Daedalus]

Good question.
I've read about three types of flushing, 1st with 134a (won't help I think), 2nd with a solvent for that purpose (will do the job) or 3rd with nitrogen. 4rd one owner mentioned brake cleaner and air, mmmh, ok.

Flushing with a solvent was advised to be made to each component except for the compressor or the dryer.

Dumb question: I'm letting it recharge at a shop but how to flush as a DIY? I don't intend to bring the car for repair to them. Hopeless?

From what I've read I think you're supposed to skip the expansion valve as well as the compressor and the receiver. I'm in the same boat as you, and am learning as I go. I've done a handful of recharges, but no flushes yet. I need to flush an old system on another car that has been open for several years. I'm staying with R-12, but I need to get all the old oil out so I can add the proper amount of new oil. I'll be using a pressurized solvent flush (kwik klean, fast evaporating), followed up with dry compressed air. The dried air seems like overkill to me--won't the receiver trap any moisture in the system, plus the vacuum before the recharge should remove most/all moisture beforehand, right? But that is what is recommended by the "pros" on a couple sites I've read.

I would avoid brake cleaner and R-134a. I'm using a solvent so I assume it works. Make sure you backflush the items, going in the opposite direction of normal flow. I've also read of people using oil (pag/poe) to flush out the old mineral oil. But you still have the problem of knowing how much is in the system before adding more.

An excellent mobile AC forum

More info

I find the more I read the more conflicting info I find.

 

[goldNSX]

An excellent mobile AC forum

More info

I find the more I read the more conflicting info I find.

So true! I never learn out. Sometimes I get the picture of some A/C 'forums' like: it's dangerous! Bring us your car and we do it for you $$$$ (including and extended test drive of course).

As I thought, brake cleaner and R134a is a quick and dirty method the hole system won't like.

I came accross that A/C forum too. Good infos.

 

[slebidia]

I've done quite a few R12 to R134a conversions on my CRXs and Civics. I usually pull as much of the system apart as I can and flush with denatured alcohol and compressed air. Flush the compressor as well but follow the service manual instructions on how much oil to pre-fill it with before charging.

 

[goldNSX]

I had a closer look at the A/C compressor yesterday and it's obviously leaking. It's not the hoses but I guess the connection of them to the compressor. I have to get the front beam out first. If I'm lucky it's only the two o-rings and the fitting 'o-ring' which can be changed. Any thoughts?

 

[davidf]

I'm curious! Why are you going 134? Is R12 that hard to get hold of nowadays. I have a case stored in my closet but can still buy it from certain vendors for my job. I'm just curious is all.:smile:

 

[goldNSX]

Yes, R12 is very hard to get and with a leaking A/C it hurts my environmental responsability.

I've attached some pics of the underbody showing white stains. I wash it once a year, so it catchs my eye. One A/C hose looks a little bit confusing. Any thoughts on this? Normal or out of range?

 

[davidf]

Of all the leaky Ac systems I've seen over the years, none have left white stains. Oily stains but not white.

 

[Zennsx]

According to the SM on page 22-82 the compressor has some kind of an oil reservoir where it says: 'Don't let any compressor oil run out' while dismounting the relief valve. So I'm a bit confused about the oil amounts in the A/C system.

I've seen on a list that the A/C of an 93-02 NSX has 30 oz. of freon and 5.0 oz/850 gr of PAG. I can't remember that anybody ever put 5.0 oz/140 gr of PAG in the system during a complete recharging. And I had to recharge quite a lot in the past 8 years due to a leak which finally be fixed next month (with all o-rings). It was somewhat like 20 grams. Maybe they did an error but if not where is the rest of the oil: A/C compressor, no?
I've searched the internet up and down and one guy said that for the Honda conversion kit the compressor has to go out, drained of the old mineral oil and filled with PAG. The retrofit service bulletin says just to put the whole bottle in the system (it didn't say compressor).

Did I confuse you definitely?

This is correct, the compressor in fact does have a resevoir which is topped off with Pag oil upon its installation.

 

[ralph cerbone]

i've been following this thread closely,most of the feed back back is semi accurate,(daedlus sounds to be accurate )a 134a conversion is only done when all components are drained(hoses included),oil measured &replaced,all o-rings changed,drier included and this is the bare minimum,(a full conversion will break the bank) but this method will work, you should not use compressed air because i know no one or shop has the compressor driers installed that can meet the spec for that air, yea i know there will be guys that disagree with me because they have done it and it works,however when you play this game the end does not always justify the means (we are looking for longevity of service not just to get thru a season of cooling). take your time ,look at every component ,you 'll be ok, the key is to watch when they pull a vacuum on the system, at 26" if the gauge hangs there for a while you have moisture in the system ,let them evacuate longer,
I started dealing with this refrigerant in the late 80's ,we tried to anticipate all problems, i never stop learning, by the way i am not impressed with that a/c forum , good luck!!!!