Unless I am missing something, this is leaking there the low pressure hose connects to the top of the accumulator. Yes, I used dye when I replaced my compressor. Yes, I used Nylog sealant/lube. Yes, I changed the gaskets. Having written this, I suspect that everything is still working for now. I replaced the accumulator when I replaced the compressor.
clean it all off, take the spring clamp off the suction hose, and run it. ive seen the fittings leak where they are welded to the hoses. since the oil is up high, indicates leak is high. if it was the lower oring, typically the oil wont go up.
It must have done this when I used the A/C to help out the defrost once. If it matters, it would have been pretty cold out when I did this, and normally, I don't use the A/C with defrost (it's not automatic on this car). It definitely was not like this when I was replacing the head gasket. I would have noticed that.
Mine looked just like that when I had fixed my AC last time. Despite how it looked, for me, it was the electric control unit next to that hose that wasn't sealing well and I guess there was some spray? I heard the hiss finally after putting it on vacuum. There was almost no residue at where the electrical connector is screwed in. There was the green accumulation like you have on top of the ring around the low side hose. Which made me think it was leaking there but wasn't. 2 cents.
So the fix for you was a new O ring or was it the pressure switch (You referred to it as electric control unit)?
the cycling switch.. if you suspect a leak, replace it. i agree with dc that sometimes you will get oil next to an area that is leaking.. BUT ac refrigerant is heavier than air, and with the under hood air flow, it is verrrrry unlikely that the PAG oil and dye will go 'up' as seen on the suction hose..
there should be a schrader valve on the accumulator where the cycling switch screws into. under ideal conditions you should be able to remove and replace the switch without recovering and recharging.
My fix was replacing the O ring. The O ring my new accumulator came with was a bit flat and had this little imperfection on one edge (tho flatness matched my original O ring on my old accumator). When I had removed the switch, I had noticed it was really really easy to twist off. So I dint tighten it down as much as I should have? But anyhow upon second "attempt" I went ahead and changed out to another new O ring. There was dye and freon on the valve for the switch. The hiss from the leak is probably not noticeable with any amount of ambient noise. I only barely heard it in the quiet right after turning off the vacuum pump a few times.
The leak is where the low pressure line connects, at the spring clamp on the right side of the first picture. I was cleaning it, and had sudsy water on it, and decided to turn it on and see where it would bubble from.
It's a good thing that I did that when I did. I tried to turn on the AC yesterday and it didn't work. Presumably because it all leaked out! If I had waited I would have had to recharge it just to find the leak and wasted a charge.
Yes the plastic thing did work better. Presumably because it's thinner. The metal ones might work better if they were beveled, or something. Got it apart, replaced the orings, even through there was nothing visibly wrong with the old ones. Put on a bunch of Nylog Blue, and it still won't hold a vacuum. Now you know why I'm so grumpy! I'm going to try pressurizing the system (I have a home made adapter to put in compressed air) and try spraying everything with soapy water next.
If you deliberately pressurize it with air, you'll saturate the dehumidifier bag in the receiver/drier and have to replace it. A can of R134 is only $5 at Walmart, enough to pressurize it for leak testing.
don't put air in it, you'll ruin the dryer. you need a halogen detector... also, did you replace the charge port valves? before you do anything else with the system, replace the charge port valves.
Yeah, if I had a way to dry the air it would be better. It's been done before yes. Plus those are the easiest places to test for leaks with soapy water.