A/C Compressor Rebuild article

[Rod Walter]

Wayne just put a tech article on the site in which I documented a rebuild of the Nippondenso A/C compressor on my car. It was a fairly easy job and meant to fix a shaft seal leak. Leaks at the compressor usually show up as traces of refrigerant oil and I noticed some on the compressor mount just below the clutch assembly.

If you would like to take a look click here.

This won't help if your compressor is siezed but is a good opportunity to check its overall condition and prevent any Freon from leaking via the compressor. Please let me know if the article is unclear anywhere or could use some editing (one of the pictures is shown twice and we're fixing that along with a typo).

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Rod Walter
'88 911 coupe

[orbmedia]

Nice article. Where do you buy the rebuild kits?

[Rod Walter]

Orb, I bought the rebuild kits from www.ACSource.com but I think that Wayne is working on making them available from Pelican.

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Rod Walter
'88 911 coupe

[This message has been edited by Rod Walter (edited 08-07-2001).]

[jlex]

Rod:
I haven't looked at the article yet, but it sounds like something I should tend to. I've noticed a bit of refrigerant oil on the inside of my engine deck lid above the compressor... apparently, the movement of the shaft will fling it outwards and make a narrow line of oil which can be seen just above the compressor. Others may want to look there to see if they've got the tell-tale line signaling a seal may be going. Thanks for taking the time to do the article.
regards,
jlex.

[jlex]

Good article, Rod; will have to print it out. I do have a question, though... don't you have to replace the dryer once you've opened up the system? I thought that it would be necessary before the system is recharged... Let us know. Thanks.
jlex.

[Rod Walter]

Jlex, the common wisdom seems to be that if the system is open for less than 24 hours and properly "plugged" then the receiver/dryer doesn't need to be replaced. But if the system has been empty for a long time or open for more than 24 hours you are right - the dryer should be replaced. The A/C technician should vacuum down the system before charging to remove moisture so that the dryer doesn't have to work as hard. If your car still has the original dryer it isn't a bad idea to replace it anyway.

When I bought my car the system had no Freon in it. So, before charging it in the spring I did replace the dryer and then charged it. Unfortunately, the shaft leak doesn't easily show without a charge thus the purge and rebuild after the spring charge. You can pull a vacuum on the system to check generally for leaks but it won't pinpoint the source. As a matter of fact, after the rebuild I did place a vacuum on the system to check my work, left my gauges in place, and it held for well over 24 hours - so I was pleased!

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Rod Walter
'88 911 coupe

[Joeaksa]

Rod,

Remember in the far reaches of my grey matter that you could "bake" a dryer to remove the moisture from it and reuse it. Assume that they were referring to putting it in the oven for several hours at a low temp to get the moisture out. Has anyone ever heard of this and if so, does it work?

JA

[wckrause]

It's 103 degrees in Minneapolis today. I wish I had an AC compressor to rebuild!



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Bill Krause
'79 911SC Euro
MY PELICAN GALLERY

[964Cab]

I just ck'd and I have the same Denco compressor in both the 964 '90 and '95 993. But the latter uses the newer frig type.

[Mrdi]

So..
Have you run with the air on yet to see if the leak is gone?

[Rod Walter]

Mrdi, of course! It's been 95/95 here for the past couple of weeks (degrees/humidity) I'm able to stay very comfortable in the car with vent temps around 40 - 45 degrees F.

964Cab, the rebuild kits state that the seals and o-rings are for either R-12 or R134a which tells us two things: 1) If you switch from R-12 to R134a you don't need to do anything to the compressor except empty the oil, and 2) everything in the article still applies to the same compressor using the newer refrigerant.

Joe, yours is the first suggestion I've seen about baking the old dryer. The idea appeals to a cheapskate like me - now I wish that I hadn't thrown away the old dryer!

Bill, wish I had more to offer but maybe you can hire a young lovely to sit passenger-side and fan you as you cruise around town.



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Rod Walter
'88 911 coupe

[964Cab]

Since I have no A/C cold what-so-ever can I just unhook the compressor and take it off and replace the various seals ? Do I have to run the motor for an extended time to re-charge the system with the newer type A/C fluid ? Where is the dryer on a 964 ?



[This message has been edited by 964Cab (edited 08-08-2001).]

[brayne]

Rod,
Thanks for creating this article for replacing the seals on an a/c compressor. I look forward to doing this job myself since like yours, my compressor sprays some oil from the nose seal but otherwise functions well. Do you have a recommendation for a particular brand of R12 compatible refrigerant oil? Thank you!

[Mrdi]

Rod,
Was this done on your 88-911 ?

[Rod Walter]

964Cab, if you are confident that there is no refrigerant in your system then, yes, you can just open it up. But don't waste money or your time if you're not sure that you have a leak at the compressor shaft. If you wish to change over to R134a you will have to make certain that you empty the system of its current refrigerant oil as much as possible and then replace it with one of the newer oils - a total of ~5 oz. according to Bentley. And you shouldn't run the system at all until the refrigerant is in because the components depend upon the refrigerant to circulate the oil.

If you're thinking about changing over to R134a yourself you should know that the system's capacity with it is only 80% of its R-12 capacity - on my car that would be 38 oz. of R134a. And you really should have a set of gauges as well as a vacuum pump to clean the system prior to charging it.

I don't know about your car but on mine the dryer is located in the wheel well behind the left front wheel.

Brayne, the system uses simple mineral oil so I felt comfortable just going to Autozone and picking up a quart marked "R-12 Refrigerant Oil" for about $5 - although that's way more than you need. I'll find other uses for it. Surely it's available in smaller packages.

Mrdi, yes this was on my '88 911. How is the A/C on yours?

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Rod Walter
'88 911 coupe

[This message has been edited by Rod Walter (edited 08-08-2001).]

[964Cab]

Thanks,

I'm going to take the compressor off and store the belt until the whole system is cleaned out. I'll try and re-new the compressor internals myself. I see Salvo sells the newer refrig stuff but I didn't know we the public could still buy the older R-12 ? I'd rather use R-12 despite the cost.

Many thanks,
BTW: The same company that made my '90C4 Cab 964 a/c compressor also made my '95C2Cab's a/c compressor although the latter uses of course the newer refrig.




[This message has been edited by 964Cab (edited 08-08-2001).]

[Rod Walter]

964Cab, the general public cannot buy R-12 without EPA "dispensation." In other words, you must have what is known as a section 609 certificate. Then you can buy R-12 at Autozone for $34.95 per 12 oz. can - and you would need four of those to fill the system in my car (don't know the capacity of yours). This may sound expensive but I saw one place charging $90 a lb. for Freon so that's actually not that bad.

If you would like to get your 609 license you can go to either www.epatest.com or www.imaca.org, pay $20 and take an open book, on-line test to get the certificate. You can have the test open in one browser window and the free, on-line study guide in another. Pass the test and you, too, can have the permission of the EPA to buy Freon.

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Rod Walter
'88 911 coupe

[This message has been edited by Rod Walter (edited 08-08-2001).]

[This message has been edited by Rod Walter (edited 08-08-2001).]

[964Cab]

I might as well just upgrade as I have to take the a/c compressure off anyway. Salvo sells all the tools required as well as the newer frig materails, not sure of the compressor oil though.

[964Cab]

Rod: I read that .pdf file and it states that the older compressor should have it's internal seals updated to the newer frig seals if you want to change to the newer frig type (and of course new oil type as well). Since it's a '90 C4 I might as well get a new dryer, is that located under the left front fender ?

Many thanks

[This message has been edited by 964Cab (edited 08-09-2001).]

[orbmedia]

This thread has prompted me to dust off a few good used units and place them for sale for anyone interested in using them. See the for sale forum.

http://www.pelicanparts.com/ultimate/Forum12/HTML/003711.html