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Nitrogen and 134A

extramile on Tue July 28, 2009 1:04 PM User is offline

Country of Origin: Canada

Posted last week about the JD Combime. I have purchased a good leak detector so now I need more advice. I really suspect it is a shaft seal leak. The system holds 4lbs so if I put in 1 pound of 134A and pressurize with Nitrogen will that be enough to find leak. Can I run the system with Nitrogen and freon mixed to activate the leak on the shaft seal ???

mk378 on Tue July 28, 2009 1:29 PM User is offline

Put in R-134a to get to about 30 psi (should only take a few oz) then fill with nitrogen to 150-200. Absolutely do not run the compressor like that. You can turn it by hand though.

extramile on Tue July 28, 2009 2:16 PM User is offline

If I put my leak detector at the front of the compressor and turn it by hand a couple of times will that be enough to make the alarm go off ????

TRB on Tue July 28, 2009 2:50 PM User is offlineView users profile

If your having trouble finding a shaft seal leak. Place a shower cap over the clutch assembly and let it sit for awhile. The insert your probe inside the shower cap and see if it go's off.


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mk378 on Tue July 28, 2009 2:55 PM User is offline

Some compressors you can easily remove the shaft nut and slide the clutch plate off (be careful not to lose any shim washers). Then you can sniff right at the seal.

GM Tech on Tue July 28, 2009 3:05 PM User is offline

I've gently pushed the clutch side to side- apply small amount of pressure with your thumb-- and heard them hiss- or rotate it and hear them hiss-- no leak detector needed for that....there should be an oil sling about front of compressor as well......lots of dirt to contend with on farm equipment.....

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

extramile on Tue July 28, 2009 11:19 PM User is offline

JD puts a cover on their clutch so I removed it, added 134 and then put up to 200 pounds of nitrogen. Rotated compressor by hand. Had the leak detector go off a couple of times in front of clutch but then couldn't get it to go off again. The compressor is in such a bad spot I can barely reach it. The Combine is only 4 years old and when my guy bought it he had the dealer charge it cuz it was leaking then. Everything else on this unit is bone dry and no oil spots anywhere.
I think I'm gonna charge system, add dye and let him run it for a couple of days harvesting wheat then re examine for leaks. Customer is a buddy so trial and error is a little easier. I have worked on a lot of highway trucks and farm equipment but have never had one stump me like this. If anyone else has a better idea please comment. Everyone on the site is very helpful, would be lost without you guys.

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