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post #1 of 19 (permalink) Old 12-12-2012, 05:56 PM Thread Starter
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Question New compressor leaking shaft seals

A short time ago I replaced my compressor with a new Sanden SD507 compressor. It pulled almost 30 inches vacuum. When I pressurized it with R-134A you could hear the freon gushing out the shaft seal.

So I'm thinking I got a bad compressor off the shelf. However, since I had the compressor in a box for about a year, a warranty never entered the picture.

So recently I bought another "new" compressor. And it did look new. I added the correct oil as prescribed by Sanden (6oz. of 500 mineral oil). I pulled vacuum once again and got good numbers so I proceeded to add freon. Once again it gushed out the shaft seals. I also noticed mineral oil on the floor beneath the unit.

I am at a loss. The compressor was delivered dry. I added the oil on the workbench and turned the shaft by hand to distribute the oil inside the unit.

I've done this on more than a few old Hondas with great success so I'm confident in my procedures.

The unit available for my 86 Graduate from IAP didn't work as mine has flare fittings as opposed to o-rings (see attached pic). Also the flange dimensions are different. They accepted it as a return and could help no further. I must have a European model Alfa or something. No one I have found can explain why I have this oddball compressor.

Anyway I'm thinking that both these compressors probably sat on a warehouse shelf for a long time and the seals simply dried out. Before I invest in another unit I need to know what is going on.

Has anyone got any idea what is going on here?
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Last edited by trojwl; 12-12-2012 at 05:59 PM.
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post #2 of 19 (permalink) Old 12-12-2012, 06:40 PM
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You're using mineral oil with R-134a? Should be PAG or Ester.

I'd return the new compressor and take the previous one to a local shop and have them replace the front seal. Ask them what they think.

I got no ideal how you could get two compressors in a row with bad seals, or how it would pull a steady vacuum and yet blow the refrigerant. Unless the seals were damaged when the pulley's were put on. Did the compressors come with the pulleys, or did you install them?

Go to the supplier list and look under A/C. There are several suppliers that might have adapters, or just replace the compressor head with the correct fittings. Compressors are pretty standard world-wide.

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post #3 of 19 (permalink) Old 12-12-2012, 07:05 PM Thread Starter
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I got the recomendations from two different sources.

I noticed some oil on the floor after pulling vacuum and before adding freon. Since I had everything back together I decided to try adding freon anyway.
Seems like, even with the wrong oil, it would have taken some amount of time to destroy the seals. Besides the seals were probably meant for R-12 (and thus mineral oil) anyway. I was more concerned with the viscosity and got the oil from NAPA. That was probably a large part of my undoing.

The pulleys came installed on both units by different vendors.

Thanks for input. I still have first failed unit. We have a local rebuilder who sells a lot of units on internet. I will probably take that unit to him. Also I will get advice on oil too.

It is a real pain in the butt replacing the unit. However with all the practice I'm getting much quicker at it. Just put car on scissors lift, drain and remove radiator and then fish out the four mounting bolts.

Not as much fun as it sounds to say the least.
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post #4 of 19 (permalink) Old 12-12-2012, 07:17 PM
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The wrong oil shouldn't cause the instant leak, however if you use mineral oil with R-134a, you'll probably destroy the compressor and "black death" your entire system in short order. R-134 will not carry mineral oil through the system. You should attempt to drain as much of the old mineral oil as possible from the system, and use Ester oil with the R-134. Ester is tolerant of the small amount residual mineral oil left after draining. PAG is not compatible. I would only use PAG if the system was purged and flushed of all the old mineral oil.

If using R12, then use mineral oil.

When you say recommendations, are you saying someone told you use mineral oil with R-134? If so, they are very expensively dead wrong.

You didn't hook the hoses up backwards by some strange chance, did you? You shouldn't be able to but with the fittings problems you said you have, I just wanted to check.

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post #5 of 19 (permalink) Old 12-13-2012, 05:11 AM Thread Starter
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Impossible to hook hoses up backwards.

All oil should still be residing in compressor. When I get shaft seals repaired I will reinstall with correct oil.

And as far as the first replacement unit goes, I now remember that the first unit came with oil already in it. They probably had oil designed for R-12 in it.
If I had realized this and drain/replaced oil, the first one may have worked.

I got the recommendations off of two different charts on Sanden compressors. They both looked authoritative to me. I should have realized that they were meant for R-12.

Might be a while before I get time to do this all over again. Will post results in this thread.

thanks

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post #6 of 19 (permalink) Old 12-16-2012, 05:56 AM
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Could not find on your posts if, when you pulled the 30 " Hg for how long you did that, and if you afterward, checked for leakage in vacuo. You just say pulled 30" vac. tHING is, just pulling a vac is not enough. A vac is for removing most of the water, not checking for leakage. Fot that, you have to PRESSURIZE the system. It is well known that leak checking can not be done solely with a vac. Seals behave differently during vac as compared to pressure. had you done that, you would have avoided al the wasted gas/time.

You can pressurize with nitrogen. (or low cost propane, but have to be careful).

Yes, road is right about ester vs mineral. Why even bother with mineral. The beauty of ester is it is compatable with any refrigerant, so if you even want to change to a different gas, no problem.

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Last edited by Joe Papa Sr; 12-16-2012 at 05:58 AM.
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post #7 of 19 (permalink) Old 12-16-2012, 05:57 AM
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main concern for oil is to lube comp, not "carry" it around the system.

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post #8 of 19 (permalink) Old 12-16-2012, 09:24 AM
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Yes, the compressor is the main user of lubrication, however, if the oil is not miscible with the refrigerant (e.g. mineral oil and R-134), the mineral oil can accumulate in low spots of the system and not be returned or cycled through the compressor to keep it lubricated.

Bottom line. Don't get cheap with a conversion. Cheap is usually a good way to get expensive.

1. Drain/purge as much of the old mineral oil out of the system as possible. I'd remove the condenser and flush it out with mineral spirits. Let the hoses drain as well. The evaporator is a lot tougher to get to, so I just gently blew out as much as practical. The old receiver drier get chucked in the garbage.
2. Replace the 0-rings with buna R-134 ones. (Cheap) If you've got a fitting that just doesn't want to come off, leave it. The existing 0-ring is probably coated with "gunk" and won't leak R-134 hardly at all.
3. Replace the receiver drier. ($50)
4. Replace the expansion valve with a R-134 calibrated one. ($30)
5. Replace the condenser with a Parallel Flow, if best performance is desired. (about $110 for a 164-size one)
6. Use Ester oil unless system was completely purged of mineral oil. If zero residual mineral oil is in the system, use PAG.
7. Pull a vacuum in the system, just like you would with R-12.
8. R-134 charge will be about 80% of the normal R-12 charge. A slight undercharge is better than any overcharge.

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Last edited by Roadtrip; 12-16-2012 at 09:31 AM.
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post #9 of 19 (permalink) Old 12-16-2012, 04:04 PM
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yes, John (roadtrip), good point on the oil being misceable, for sure (I should have clarified- my fault). I would never use an oil not compatable with the gas....

Only thing I might ad to above John's list is- most ac pros dont recommend washing/rinsing out a condenser- not practical, not even very effective. Like you said above "dont get cheap with a conversion", so dont try to wash out a condenser and hope you got every scrap /shard/particle out cuz it rarely happens. Buy a new one.

Also, puling a vac, again, I emphasise, is not the way to verify if the system is leakproof. It is only a way to pull a vac, and thats it. Yes, you should be oK if you get lucky, but he already has wasted so much gas on it.

Lastly, dont assume because youre reading 30 " Hg on vac, you actually are at that vac cuz most of those guages are waaaay off. By 5-10% error.

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post #10 of 19 (permalink) Old 12-16-2012, 04:48 PM Thread Starter
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Actually I wasted very little freon. I could her it hissing out from under the pulleys almost immediately. Also the oil never had a chance to circulate so I am assuming most, if not all, is still resident in the compressor. Also I have been using the green buna-n o-rings.

It did hold vacuum for ten or fifteen minutes, but I can see where, due to its construction, a seal would work better with the positive pressure on one side as opposed to being on the opposite (and wrong) side - which is what happens when you are pulling vacuum.

It is still baffling to me that, even though I had wrong oil in it, it still should not have damaged the seals in such a very short period of time. I mean we are talking literally seconds. I have to think the seals were dried out before I even started from maybe sitting in a hot warehouse for a long time (which due to rarity of this particular unit, could have happened).

I think if I take compressor, drain the oil, take to to get AC rebuilder to get shaft seal replaced (assuming it is signficantly cheaper than rebuilding entire unit), put in the ester oil, reinstall, pull vacuum. and then charge it with freon, I should come out OK. Since compressor is at low point in system, gravity should be my ally.

Also, since the system holds only a small amount of freon (compared to most other systems I've seen), can I expect adequate cooling of the interior?

I have done the same AC job on my 1982 Porsche 911, and it actually cools quite well.

And by the way, Merry Christmas guys.

Warren
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post #11 of 19 (permalink) Old 12-19-2012, 05:04 PM
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Actually I wasted very little freon. I could her it hissing out from under the pulleys almost immediately. Also the oil never had a chance to circulate so I am assuming most, if not all, is still resident in the compressor. Also I have been using the green buna-n o-rings.

It did hold vacuum for ten or fifteen minutes, but I can see where, due to its construction, a seal would work better with the positive pressure on one side as opposed to being on the opposite (and wrong) side - which is what happens when you are pulling vacuum.

It is still baffling to me that, even though I had wrong oil in it, it still should not have damaged the seals in such a very short period of time. I mean we are talking literally seconds. I have to think the seals were dried out before I even started from maybe sitting in a hot warehouse for a long time (which due to rarity of this particular unit, could have happened).

I think if I take compressor, drain the oil, take to to get AC rebuilder to get shaft seal replaced (assuming it is signficantly cheaper than rebuilding entire unit), put in the ester oil, reinstall, pull vacuum. and then charge it with freon, I should come out OK. Since compressor is at low point in system, gravity should be my ally.

Also, since the system holds only a small amount of freon (compared to most other systems I've seen), can I expect adequate cooling of the interior?

I have done the same AC job on my 1982 Porsche 911, and it actually cools quite well.


Warren
Well, if you use R12 instead of r134a, yes, should cool pretty well. The blowers are pretty weak on our cars. Thats the achilles heel. Also, better that r134a is HC gas. Its sooo easy to use. No need to worry about a tad of moistyre either. Dont smoke when putting it in.

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post #12 of 19 (permalink) Old 12-20-2012, 05:25 AM
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Yea. If the compressor has disintegrated and shows any evidence of black death, the condenser is junk. You'll never be able to clean it. Even trying to drain it thoroughly of clean oil is difficult. Hopefully the filter in the receiver drier catches the burned aluminum particles and prevents the expansion valve and evaporator from being contaminated.

Regardless, I'd drain as much old mineral oil out of the system as possible. When we talk about "low" points in the system, there are low points all over. Condenser, R/D, Evaporator, etc, not just the compressor. I'd change the receiver drier anytime any type of conversion was done, even with a clean system.

Too much oil in the system degrades the efficiency and affects cooling.

I've used Envirosafe ES-12 in an old Jeep conversion, and it does work extremely well, is very inexpensive, works with mineral oil fine, and is basically a drop-in for R-12. And you do use much less of it than the original R-12 charge. Not all states approve it, however, and there is the ongoing questions about exactly how safe it is to use. For sure, you want the system to be sealed up well, especially inside the pax compartment.

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post #13 of 19 (permalink) Old 12-20-2012, 05:32 AM Thread Starter
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The compressor has never been run (i.e clutch engaged with engine running). It leaked as I was adding freon. The only thing wrong with unit should be shaft seals.

Please reread my posts.

I do appreciate response however.

Thanks
Warren
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post #14 of 19 (permalink) Old 12-20-2012, 05:35 AM
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Yes, your system should be clean.

Especially with A/C, I always include those provisos for future "search" users who may come across the threads looking for advice.

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post #15 of 19 (permalink) Old 12-20-2012, 05:51 AM Thread Starter
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When I get around to replacing unit AGAIN (ugh!), I will post results.

And aren't these forums great? I've solved many problems with different cars (I also own an 82 Porsche 911SC and an 88 Honda CRX - both in great condition) using them. I don't know where I would get all this helpful information without them.

And it has saved me literally thousands of dollars.

Have a great day,

Warren
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