AC Noise

ChevyDude

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Year
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Happy Memorial Day Ladies and Gents!

As it has become fairly warm down here in South La, I was sitting in my truck yesterday letting things cool off when I heard a noise from under the hood. I raised the hood and looked for the obvious, like a thrown belt, didn't find anything. Thinking back a little I realized that the AC probably was not cooling....maybe. I got back in the truck and things were cooling off. Drove about 60 miles last night without any problems. Today I notice a black cap on the concrete driveway. It's the one in the photo with the oil around it. Looks like the line going to the dryer and evidently it "blew off" yesterday while I was in the truck.

Any ideas? Leaking shredder?

Thanks in advance.
 

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billr

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Are you suspecting a leaking Schrader valve? Yeah, seems likely.
 

ChevyDude

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Are you suspecting a leaking Schrader valve? Yeah, seems likely.
Well, I'm just a practical and logical thinker, you guys are the experts. I just cranked it up and at idle it seems to be cooling. Could it be cooling better? Probably so. I checked for bubbles with soap and water and don't see anything obvious. Are Schraders famous for leaking? Pardon my misspell. I think I was a victim of autocorrect. :)

Thanks a bunch.
 

billr

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The easy way to check for leaks is with a common UV light. This vehicle was manufactured with UV dye in the refrigerant/oil, I feel sure.

What is your goal here? If you are going to try to "tune up" an A/C system, you are going to soon need a high/low gauge set. For anything resembling repair you will also need a good vacuum pump.

When I first read "shredder", I first thought of machinery to, um... shred paper/metal/vegetation. I was struggling to figure out how it had anything to do with your A/C. If you had wrote "shredder valve" I would have got there sooner!
 

ChevyDude

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The easy way to check for leaks is with a common UV light. This vehicle was manufactured with UV dye in the refrigerant/oil, I feel sure.

What is your goal here? If you are going to try to "tune up" an A/C system, you are going to soon need a high/low gauge set. For anything resembling repair you will also need a good vacuum pump.

When I first read "shredder", I first thought of machinery to, um... shred paper/metal/vegetation. I was struggling to figure out how it had anything to do with your A/C. If you had wrote "shredder valve" I would have got there sooner!
Have you ever seen a Shrader valve cap blow off like that?
 

ChevyDude

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No unless it was left loose to begin with. Cap has a rubber seal inside so if the schraeder valve does start to leak the cap seals the leak
The interesting thing about the two Shrader valve caps in the photo is that neither of them have internal threads. They more or less just push on. First time I have seen those.
 

billr

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I am of the opposite opinion: Those plastic caps are just to keep crud out. No way is the high-side one going to hold 250+ psig pressure. The caps are not even glass-filled plastic. And don't forget the heat they are subject to...

The cap threads are external ones, on the part that goes down into the Schrader valve; about 5/16" diameter.
 

grcauto

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If it were leaking enough to blow off the cap it would be discharged in short order.
 

Mobile Dan

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Poor boy diagnosis is to spit big on two fingers, then drag the spit over the shredder hole and see if the leaking valve blows a bubble.
 

billr

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Grcauto and dabunk,

I think you are only considering a sudden big leak at the Schrader. A slow leak could build up pressure under the cap, if the cap does try to seal, until the cap blew; but with little loss of refrig/oil volume. Of course, with a slow leak (any leak) the charge will still be lost eventually and cooling stop. I waiting to see if the OP continues to have cooling...
 

paulo57509

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Just from the oily and attracted grime in the area around the port, I'd say there's some leakage going on.
 

dabunk

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Grcauto and dabunk,

I think you are only considering a sudden big leak at the Schrader. A slow leak could build up pressure under the cap, if the cap does try to seal, until the cap blew; but with little loss of refrig/oil volume. Of course, with a slow leak (any leak) the charge will still be lost eventually and cooling stop. I waiting to see if the OP continues to have cooling...
Personal experience on vehicles with AC has been different than that. Only speaking about what I have seen with my own eyes.
 
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