Automotive Air Conditioning Information Forum (Archives)

johnboy123 on Tue July 16, 2013 1:47 AM

Year: 1995
Make: Chevrolet
Model: Suburban
Engine Size: 5.7
Refrigerant Type: R-134a
Ambient Temp: 80
Pressure Low: 45
Pressure High: 275
Country of Origin: United States

Front and rear AC system...takes a HUGE amount of freon to charge. Loses a significant amount of charge in a month or two. Loaded with UV dye. UV light detects nothing; hoses are fine, connections, receiver dryer, behind receiver dryer, condenser, lines to compressor...chased the whole system...even went under the truck to see if the rear lines were leaking. The whole thing checks out...no dye on the underside of the hood. I would think I would see a river of dye by now on the truck, as its been charged twice this summer already. Can you leak freon and NOT oil/dye?

Jag987 on Tue July 16, 2013 2:15 AM

I understand your frustration. I searched for a leak on my own car for two summers. Could not find anything with an electronic leak detector. would randomly get hits, but never enough to track down. Never did find the dye, but the rubber hose going to the accumulator finally ended up with enough oil on it that I knew it was not coming from the oil pan leak (stupid design, have to remove engine to replace pan gasket). I wish you good luck in your search.

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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!

mk378 on Tue July 16, 2013 2:54 AM

GM compressors leak at the shaft seal-- pull the clutch plate and look for oil / dye there. Check the lines underneath the truck to the rear. Check evaporator drains for dye. Dye is carried by the oil, it only comes out while the system is running and blowing oil around. When parked most leaks only lose gas.

GM Tech on Tue July 16, 2013 6:04 AM

Number one leak location- compressor shaft seal R4 compressor that year

number two- compressor shell O-rings

number three- rear lines at each grommet- or under rubber insulated coverings

number four- front evaporator- pull drain tube and shine black light up it's throat..

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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......

Cussboy on Tue July 16, 2013 9:50 AM

We had a 1994 Suburban with 5.7 engine and R4 compressor from 2000 through 2010, in Arizona. We had the compressor replaced at least three times, due to compressor belly leaks. These were new Delphi/GM compressors, not rebuilts. AC always worked good, and we even did the "trick" of always keeping the rear AC blower fan on while running it, to help any R134a in the rear system (which had no receiver-drier or accumulator in that circuit) to vaporize, so no slug of uncompressible liquid refrigerant getting back to the compressor.

It just appears that the R4 just has that property, and we had a 1988 Suburban similarly set up, and not much different there. Now we have a 2005 Yukon, looks like much better design in its AC, especially with the accumulator connections.

Leggie on Tue July 16, 2013 1:42 PM

Quote
Originally posted by: johnboy123
Front and rear AC system...takes a HUGE amount of freon to charge. Loses a significant amount of charge in a month or two. Loaded with UV dye. UV light detects nothing; hoses are fine, connections, receiver dryer, behind receiver dryer, condenser, lines to compressor...chased the whole system...even went under the truck to see if the rear lines were leaking. The whole thing checks out...no dye on the underside of the hood. I would think I would see a river of dye by now on the truck, as its been charged twice this summer already. Can you leak freon and NOT oil/dye?


If you're losing that much, once you get suds on where the leak is, you should be hearing hissing and seeing bubbles. Get the whole compressor area covered in soapy suds.

NickD on Tue July 16, 2013 3:09 PM

You can lose dye or oil without losing refrigerant.

You can lose refrigerant without losing dye or oil.

You can lose a little bit or a lot of each.

My first choice in finding leaks is with a halogen leak detector with better than less than one ounce per year leakage sensitivity, and one with a long goose neck. Refrigerant is heavier that air so always leaks down. But must in done with a cool engine and a draft free space, and must sense below each component. Hot engine creates quite an upward draft even in a draft free space.

Have yet to run across a compressor where you can just removed the clutch disk, some need special tools. Without removing anything else. With the clutch plate removed, you can see the seal and inspect for even the slightest oil leaks visually. Can also put your electronic leak detector right next to that seal and all the way around it.

pippo on Tue July 16, 2013 7:37 PM

Leak over 1-2 months (enough leakage to not have cold ac, but still have some gas left inside, that is) is a slow leak, as I understand it. Hard to find, of course. I chased one on a civic for months. Yes, different make than a GM. Still, dont overlook the low pressure line's rubber tube. I got seepage from that "barrier" baloney hose. Smelled it myself with my nose with my own method. No elec sniffer. Slow leakage- sniffers got to be down to 100ppm sensitivity, and still, can pick up gasoline etc. Still, you can try sniffer, but theyre kinda $$.

Oh, there was never any sign of oily rubber either. Good luck, Man.

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beware of the arrival

Edited: Tue July 16, 2013 at 7:38 PM by pippo

johnboy123 on Wed July 17, 2013 10:23 PM

Thanks guys ...will look into all of that info!

NickD on Thu July 18, 2013 3:58 PM

Quote
Originally posted by: pippo
Leak over 1-2 months (enough leakage to not have cold ac, but still have some gas left inside, that is) is a slow leak, as I understand it. Hard to find, of course. I chased one on a civic for months. Yes, different make than a GM. Still, dont overlook the low pressure line's rubber tube. I got seepage from that "barrier" baloney hose. Smelled it myself with my nose with my own method. No elec sniffer. Slow leakage- sniffers got to be down to 100ppm sensitivity, and still, can pick up gasoline etc. Still, you can try sniffer, but theyre kinda $$.


MVAC is one of the very few fields of discipline that I know of where you get a payback on the basic equipment the first time you use it. After that, its all gravy.

webbch on Thu July 18, 2013 5:50 PM

Hmm, why do I keep "investing" in it then? :-) The more I save doing my own work, the more tools and equipment I seem to acquire to improve the process and double check my work.

Edited: Thu July 18, 2013 at 5:51 PM by webbch

pippo on Thu July 18, 2013 8:51 PM

Right, Nick. I agree. I own a few good things too, although, aadmit, maybe not as good/$$ as some guys have here. All Im saying is there are ways to get around equipment sometimes that do work. Dont underestimate the human nose. Some - MANY forensics professionals resort to the human nose when stumped on some crime scenes' sample testings. Olfactory and memory can be very telling. Not saying we should sniff 1,1,22- tetrafluoroethane all day long, though.

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beware of the arrival