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UV Dye and Nitrogen

extramile on Tue July 21, 2009 9:41 PM User is offline

Refrigerant Type: 134A
Country of Origin: Canada


I'm working on a JD Combine and am having a hard time locating leak. I was using Nitrogen as my pressurizer and soap and water. I have always had good luck with this method until this unit. I have checked every part of this machine but cant't locate the leak. I am going to try some dye in the system and I have some questions. Can I put the dye in with the nitrogen and pressurize it up??? If I can will the dye get through the entire system??? I don't have a reclaimer so I don't want to fill the system with freon and dye as I have now way of reclaiming it. I think the leak is at the compressor seal but because of the pulley on the front of the compressor I can't get in their to spray it so I'm thinking the dye would maybe leak out the bottom.

GM Tech on Tue July 21, 2009 10:24 PM User is offline

most likely is thes haft seal-a good sniffer will prove it out....dye flows with the oil-- so if nitrogen can carry oil- it will work-- but it is my experience oil only get carried by refrigerant.

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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......

bohica2xo on Tue July 21, 2009 11:19 PM User is offline

Dye will not work with nitrogen. How big is the leak? Will it hold vacuum for an hour?

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

extramile on Wed July 22, 2009 8:19 AM User is offline

No it won't hold vacuum for an hour. When I pressurized with nitrogen it dropped from 200 to 175 in about an hour. I thought I found the leak on this unit last year but when he started it this July it was empty again. System holds about 4lbs. How much 134A do I have to put in with the dye to trace for a leak ???

GM Tech on Wed July 22, 2009 8:36 AM User is offline

Just enough to pressurize the system- like a half pound or less...but it would be good to go ahead and run the system to let dye circulate- so a full charge would be best for that- that it why I add dye to any system I service-- for future reference-- I have it premixed in my oil jug- for all vehicles...

-------------------------
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......

bohica2xo on Wed July 22, 2009 10:24 AM User is offline

To clarify, a half pound of refrigerant will not find a leak with dye either. A small charge will work with a sniffer, but it does not appear that you own one of those.

Given that you do not have a huge hissing leak, put a full charge in the system with dye and run it. Make sure you have enough oil in the system. It sounds like you have a small leak, and running it with dye will eventually show you where it is. 4 lbs of 134a is cheap compared to a good leak sniffer, so if you do not do this type of work on a regular basis then you may not want to invest in a sniffer.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

marvin-miller on Mon July 27, 2009 3:01 AM User is offline

Just a thought but your post reminded me of something my A/C instructor said years ago. He mentioned doing service calls on heavy duty equipment every year because the A/C would stop working. He also could never find a leak and what he determined was that because the A/C was never used in the off-season the oil covering the shaft seal would eventually drip off the face of the seal causing a shaft seal leak.

His thoughts were that it's actually the oil (as opposed to the seal) that does the brunt of the sealing. I personally believe him to be correct in this. I think the reason it doesn't happen more in vehicles is because when you turn the defroster on the A/C runs so even in the 'off season' the compressor seal gets lubrication.

In my instructors case he was working on logging equipment. You mentioned that this was a combine and it worked last year and then when he start it up this year....

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Best & Thanks;
Marvin

Dougflas on Mon July 27, 2009 5:25 AM User is offline

If you can get a hold of a good sniffer ( I like the Tec-mate or the h-10 ), add a couple oz of refrigerant and use Nitrogen to pressurize the system. You'll find the leak especially if it's in a area you can't physically see.

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