Help with AC Leak
Thread Starter
Intermediate
Joined: Feb 2005
Posts: 32
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From: Las Vegas NV
Help with AC Leak
I replaced the compressor and accumulator on my 03 C5 last week and ran a vacuum on the system for 4 hours. All indications were that the system was sealed and leak-free. On Friday morning, I put two 12oz cans of R134A into the system plus about 3-4 oz from a third can. That should be about perfect for a system spec'd at 1.75 lbs. A test drive around the block showed at full fan I was getting 38.3 degrees from the vent. Yesterday, 3 days later, I start the car and the air from the vent is warm. I open the hood and shine a flashlight on the compressor and the clutch is not engaging. I connect my Yellow jacket gauge set and it reads zero on both low and high pressure lines. Clearly, all the freon has leaked out in the span of 3 days. This morning, I'm running the vacuum again and all indications are the system is sealed. Any ideas on what could cause this leak?
Le Mans Master
Joined: Dec 2017
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From: Virginia
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You need to do a leak test. There is a chemical that you put in the AC lines. along with the R134A. You seem to have a pretty major leak, so I would wait a day. You can then use a black light to locate the leak.
Le Mans Master
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I replaced the compressor and accumulator on my 03 C5 last week and ran a vacuum on the system for 4 hours. All indications were that the system was sealed and leak-free. On Friday morning, I put two 12oz cans of R134A into the system plus about 3-4 oz from a third can. That should be about perfect for a system spec'd at 1.75 lbs. A test drive around the block showed at full fan I was getting 38.3 degrees from the vent. Yesterday, 3 days later, I start the car and the air from the vent is warm. I open the hood and shine a flashlight on the compressor and the clutch is not engaging. I connect my Yellow jacket gauge set and it reads zero on both low and high pressure lines. Clearly, all the freon has leaked out in the span of 3 days. This morning, I'm running the vacuum again and all indications are the system is sealed. Any ideas on what could cause this leak?
Last edited by grinder11; Aug 10, 2021 at 10:51 AM.
Le Mans Master
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Did you replace the two round, flat seals at the back of the compressor? They're seal the 2 lines going into, and coming out of, the compressor. I had a major leak here. Also, did you use new O-rings at the accumulator, and elsewhere? Harbor Freight sells a nice little LED blacklight flashlight for $7 or $8, which worked well for me. Once old seals/O-rings are disturbed, they don't always seal properly again. I'd also suggest a 'sniffer', which Harbor Freight also sells, to help locate the leak if dye doesn't work. Hope this helps......
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Thread Starter
Intermediate
Joined: Feb 2005
Posts: 32
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From: Las Vegas NV
My compressor kit came with a bag of o-rings of assorted sizes and thickness. I replaced every one of them in the entire system. Also the seals on the back of the compressor where the pressure line manifold connnects. Each one was lubricated with mineral oil.
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Thread Starter
Intermediate
Joined: Feb 2005
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From: Las Vegas NV
My next freon charge will include some of that violet dye. I have a kit i bought last year for locating leaks. I happened to think of the shraeder valves on the 2 ports. I did NOT replace those. If, when I backed out the gauge connectorss, one or both of those valves did not reseat completely, that would certainly cause a leak, huh?
Melting Slicks
Joined: Apr 2019
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From: Clark, NJ
The Schrader valves in the ports can leak. I always spray them with glass cleaner after a charge and look for bubbles, then compressed air to blow out the glass cleaner. If the bubble try connecting and disconnecting the hoses a few times. If not I found NAPA carries the right Schrader.
Thread Starter
Intermediate
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From: Las Vegas NV
Intermediate
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We use a micron gauge to help determine small leaks, but in my experience when it holds a deep Vacuum for 60 minutes or more with the gauges closed and the vacuum pump off, it is often the compressor seal or a pressure relief valve causing the Freon leak.Going to 0 psi in 3 days is a big leak.
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The Schrader valves in the ports can leak. I always spray them with glass cleaner after a charge and look for bubbles, then compressed air to blow out the glass cleaner. If the bubble try connecting and disconnecting the hoses a few times. If not I found NAPA carries the right Schrader.
Last edited by grinder11; Aug 11, 2021 at 10:55 AM.
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It's been my experience that systems that show no vacuum leaks can, and do, have leaks under pressure. Not always, but it happens. The pressures have much more force than the vacuum a normal vacuum pump can achieve.......
Intermediate
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That's where that micron gauge is handy. If you can pull, and hold a 1,200 micron vacuum the system is pretty damn tight. Often as a last check we rotate the compressor shaft back and forth while watching the micron gauge,, if it jumps way up the seal is leaking. Charging the system up with 200 psi of nitrogen can also help locate the leaks. A good detector like a H10 G is also very handy.
Thread Starter
Intermediate
Joined: Feb 2005
Posts: 32
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From: Las Vegas NV
Put in a can of R134a with UV dye this morning. Almost immediately I found the low port lit up with dye. The Schrader valve is tight, but you can feel slight air pressure leaking out of the top of that port with your finger. I've ordered a valve replacement tool from Amazon that saves vacating the freon.
Race Director
Joined: Oct 2004
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Put in a can of R134a with UV dye this morning. Almost immediately I found the low port lit up with dye. The Schrader valve is tight, but you can feel slight air pressure leaking out of the top of that port with your finger. I've ordered a valve replacement tool from Amazon that saves vacating the freon.
Melting Slicks
Joined: Mar 2018
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From: California
Put in a can of R134a with UV dye this morning. Almost immediately I found the low port lit up with dye. The Schrader valve is tight, but you can feel slight air pressure leaking out of the top of that port with your finger. I've ordered a valve replacement tool from Amazon that saves vacating the freon.
What tool where is this tool ? So u don’t have to purge the system replacing the valve? I need it …