Expert A/C Help Wanted! Part 2

did you use the black light INSIDE near the vents ?

I'd think if the evaporator was leaking, some of the dye would show up there

Re: "Now that I have looked over the system the right way, I still cannot find any leaks so I am frustrated again. The PO said the system would leak down in about a weeks time, so I would think the leak would be pretty obvious. Since I could not find any trace of the dye, I opened a fitting and looked inside there. Sure enough the dye was glowing a greenish yellow color so I know the dye is visible under the black light I have. I looked under the hood above where the compressor mounts and behind the pulley and saw no traces of dye (under the black light) so I am thinking the compressor seal is "probably" not the source of the leak. If it was I would expect that the pulley would have made a nice stripe across the inside of the hood by now. I could be wrong though, God know I have been wrong enough times before. I think the only part of the system I cannot physically see is the part of the hose that is wrapped in the heat protective shield where it passes over the exhaust manifold. Other than that I am stumped. Should I cut this off and look under it, or is it unlikely that would be a place to leak. Any other ideas? None of the A/C shops here in town are willing to look at the system while it is out of the car even though they all agree it would be best to replace the leaking parts before I put the engine back in. DUH! Anyway, if anyone has any ideas of what a novice can do at this point I would really appreciate some more guidance. I wish I had a bottle of nitrogen or something so I could pressurize it and submerge it and look for bubbles. I think that I could handle! I think that would get a little expensive by the time I got the gas, regulator and fitting I would need to do that. I am still looking for a shop in the North Atlanta Metro area that will look at it for me, but until then, I will keep trying. I still have a few weeks before the engine comes back from the machine shop so I have time to mess with it. Thanks again everyone. " Tim

--------------------------------------------------------------- Hi Tim I'm far from an expert and I'm sure one will show up shortly,but in the meantime,I agree with the two replies after your post.Plus I would like to know at what pressure you are testing the system?The shop I use tests at something like 200 lbs,and they use a halide(sp?) leak detector.They were able to locate a leak in my car that emptied the system in about 1 years time! I think you should go this route,and when you repair it and go to reassemble,use a new filter/drier and NEW o-rigs at each fitting (if that type) I did and it's been good for three years now.

I had a leak in my truck a few months ago. It turned out that the filling valve was bad. With the cap on the valve, it leaked very very slowly and was un detectable with the u-v goop in the lines. The only way to feel it was to put your finger over the valve and feel the pressure build. Just another option to your problem.

=========== If it has a leak that has gone on for some time you should see oil/dirt accumulating at the spot. Look very closely, follow all the lines and I bet you will find it.

Tim,I should have said test the system for leaks at 300 lbs.You can do this by adding nitrogen to the system(assuming you just have some gaseous rerigerant in the system)

Ok, lot's of ideas flowing in. Here are some other notes to consider.

The system was completely empty when I bought the truck. The PO said it leaks down in about 1 week's time. I have not added any refrigerant or air pressure. I have simply removed the system and reassembled it in the bed of the truck. Unfortunatley, since there is no engine, there is no way to fill the system the traditional way and sniff for leaks with the usual electronic sniffer tool.

I have looked inside the vents. In fact the evaporator is removed so I have also looked inside of the evaporator box on the firewall and as far back into it as I can see. No signs of glowing dye there. Also no signs of oil or dirt in there. In fact it looks brand new in there!

I don't have access to nitrogen, though I wish I did now! It would be pretty easy to put 200psi on it and dunk the whole system into a tank and look for bubbles. That is something that even the A/C shops can't do since they have to work on them in the car. I am still looking for a shop in town that might be willing to do that for me.

Someone did mention that they found a leak once on the schraeder (sp?) valve where they fill it up. I do have dye showing up in there (low pressure side only) but I expected that since that is where they filled it from. Maybe I need to spend a little more time playing with that area.

Disclaimer: I know next to nothing about AC systems, so if these seem stupid, please excuse my ignorance.

Since the system is "empty", why can you not use air to pressurize the system for your dunk test? After the leak is located and remedied, you will have to evac and dry the system before charging, correct?

If you do indeed need nitrogen, try calling motorcycle shops that deal in motocross/offroad bikes. If they do any suspension work, they will have a nitrogen cylinder and fittings to use when they recharge rebuildable shocks. Show up near closing time with beer and a good attitude, might get it done for free.

Would a small internal leak in the compressor be detectable?

DJ

if the system has been leaking that bad, then the desiccant in the accumulator is junk by now, you should change the accumulator just because of that.. given that you are going to change it, you can go ahead and pressurize it with shop air... you can find(buy) a cheap gauge set for under

That is a very good point. I can buy one of those DIY recharge kits and just use the hose off of that. I have a good regulator and compressor here so I can just pressurize the system a little, drop it in the tank and watch for the bubbles. That is what I am going to do. Thanks for the advice. I was so concerned about getting air in the system that I forgot I had to replace the dryer anyway. Again, thanks for the idea. At least now I can start doing something again. I was getting tired of scratching my head.

Tim

NO NO NO NO

The oil will absorb moisture out of the compressed air !!!!

Crud! Back to square one again!

Re: "From: t snipped-for-privacy@hotmail.com (t_puls) NO NO NO NO Crud! Back to square one again!"

----------------------------------------------------------------Really tour best bet is to have a shop with a halide tester do it with 300 psi in the system. Do NOT use air! I've fixed about 9 or ten systems,not an expert but have gotten good results and used to run commercial units and have SOME schooling n this. Go to for the whole rundown Frankly I would reassemble the system in the truck and take it in for leak test.Don't screw around with submerging sections of it with only

100 lbs. press. etc,then dismantle it ,reinstall it and expect it to last.Just a waste of time in my opinion

there are 2 reasons I went with the compressed air

1) No one will touch this in his area with the system apart and out of the vehicle.

disregarding the potential for severe rusting of compressor parts..............

only if you want to pull and hold a vacuum for about 48 hours

that's how long it will take, even with 30 " of vacuum on it.....AND the pump MUST be running all the time, to pull the water vapor out as soon as it comes out of the oil

and don't count on the 'dessicant' in the accumulator to do much.........it's total water absorpion capacity is about 1 ml.........about one drop

Last 134 "dryer" I bought was a hollow can. The oil is the desiccant.

Must been one of them famcy "R-134a compatible" deals for older vehicles that have been retrofitted, he he he he he.

Doc

Just curious, but why on earth would they waste the valuable space under the hood with an empty can? The more I learn about A/C the less interested I am in trying to fix it at all. I am sure that will change as soon as the first hot day hits though .

any rawpots yet?

~KJ/TLGM