I started losing freon so I charged it up lasted only a couple weeks.We checked it and found a shrader valve on the low side leaking.We fixed it and charged it and it leaked out again. My A/C guy did the sniffer tests at the condenser,Evaporator all lines and compressor.Nothing.

He told me to keep the caps off of the service ports as he has seen the OEM caps couse the freon to leak out.

Anyone hear of such ?

 

Guess its worth a try....i've got a slow leak also and haven't purchased
a leak detection kit yet. Good luck.

 

If the compressor is an older one a place you have to pay special attention to is the shaft behind the belt pulley. We have found alot of nearly undetectable leaks there.

 

There was a Service Bulletin issued back in '89 or '90 about it.

If it's only holding a charge for a couple of days, that's a significant leak. I'd guess the Condensor if the Evaporator sniffs clean. It's difficult to get at - you need to remove the shroud and there still isn't much clearance. Often you don't see it until you pull it out and then you find oil on the Radiator, not the Condensor. Since you're using R134, you might just want to pull things apart and take a look. Condensor can be pressure tested with nitrogen.

 

It's the OEM a 95'. does this apply to a 95"?

 

Your AC guy needs a new sniffer. Mine will detect a leak as small as 1/4 lb in a year.

 

That's what He told me He has. Exactly ! It's a Snap On.I wonder why it's so hard to find?

 

I hope he has looked for leaks with soap bubbles. A little dishwashing liquid and water goes a long way when looking for freon leaks. As far as the shaft, it holds true for all compressors. We have found leaks behind the pulley on GM, Nissan and practically any make. Have him put nitrogen in the entire system...the leak should show up or at least be heard if its in a coil. Look for oil around ac hoses and fittings. These guys will know where the leak happens most pay attention to what they say. Good peeps on this forum.

 

Last year I had a leak also. Turned out to be the high pressure service port. The fitting, as used on many other GM systems also is a real piece of junk unlike the low pressure service port. The high pressure port screws right off the tube. System has to be evacuated, then re-pressurized.

Did not have an vacuum pump at time and had the A/C shop do it. He said it was a common part that he replaces all the time.

I cut the old one apart and all that in there is a spring and a ball. Over time the ball looses it shape and does not seal properly. When the ball is depressed by checking the high side, you disturb its seating and the problems gets worse. I have this same problem on my Silverado truck.

 

'95 uses the Nippondenso 10pa20c - shaft seal leaks for these models generally throw oil all over the hood and won't hold negative pressure; ie, a vacuum, but will leak significantly less once there's some gas. It has to have positive pressure to make the best seal.

I've never had a problem with a service port - quick connect or otherwise - though I've routinely replaced them when I've serviced something.

Again, your Vette has a pretty significant leak which is apparently hidden from view. Your guy seems to have the right stuff, but maybe just can't reach the right place.

 

I personally have never heard of the caps causing a leak--ask your AC guy to install dye in the system (some refrigerant oils have dye in them)
As the freon leaks out a film/residue is left which will show up with a black light--some areas will be harder to get to see then others (such as the evaporator) but I've even found them leaking on occasion by "black lighting" the evap drain hose---i'll usually suggest the dye if my "sniffer" has failed to help me locate the leak....JMO

 

I changed both shrader valves on high & low side,We have dye in it for over a year now.I did leave the caps off and it's over a week now and it pulls down to 52F Degrees 70 ambient Temp..Hasn't really gone down. My A/C guy said He has seen the covers cause a leak....I know.....It's Crazy.

 

Finally !!! We found it...It's at the very top of the condenser.That's why the sniffer couldn't detect it not w/o taking the top shroud off. Yellow Dye all over the place.Oh Well, there goes $700.00. Actually,I'm just glad to have cold air again.
Can't live down here in S.E. Louisiana with out it.

 

Fixed..Nice and Cold...Looks like a rock hit it at the very top and put a pinhole leak in it..unreal.I could not believe it...I should put a screen or something in front to protect it? I wonder if anybody makes one.?

 

I'd guess age - rocks put much bigger holes in things. Someone around here came up with a screen of some sort for the lower half, but it's been awhile. Of course restricting air flow isn't the best idea either.

 

Age as well but I saw the dent it made and the hole with dye all over it.

 

Dents that high are usually caused by us folks who do some work in that area - leaning on the shroud the wrong way might be all it takes. I've also seen them from the Factory and on Replacements right out of the box.

 

For a problem child with a difficult to find leak, the best approach is to pressurize the system with Nitrogen and charge with 2 oz. of R22. Electronic Leak detectors are MUCH more sensitive to R22 than 134 or 12. Also the Nitrogen pressure will force the R22 through a leak that might not be much of a leak under less pressure. The Nitrogen will apply over 200PSI everywhere. Once the leak is located, you can LEGALLY vent 2 oz. of R22 to the atmosphere. The EPA determined that it is MUCH less harmful to the atmosphere to have 2 oz. of R22 released in order to find a leak that will prevent that much or more of 12 or 134 to be released.

A good leak detector will find a leaky condensor by just putting it up in the shroud area of the Vette. The Vette has such a complete shroud that it will trap ANY refrigerant leak that is adequate to set of the detector.

Also, when using an Electronic Leak detector, remove the two electrical connections to the blower control module, the three screws that hold in this module and remove the module on the top of the evaporator housing and put the leak detector line down inside. If the evap is leaking, an adequate Electronic Leak Detector like an Inficon will pick it up.

Don't overlook the three high side sensors near the evaporator. These cars are old enough that the sensors themselves can spring a leak around the wire exits or more commonly the seal at the threaded port will have deteriorated. Remove the electrical connectors on these sensors when your sniffing.

As pointed out by a previous poster the shaft seal is a point that should be checked. If you have exhausted all other leak possibilities, remove the nut on the front of the clutch and check the end of the shaft with the nut off. That will sometiimes show a shaft leak that otherwise would be undetectable.

Good luck,