Please help diagnostic my recent AC problem.
 

First, a little bit of my AC history...
I bought the car with almost original AC system, 12R with an after market condensor on the deck lid.
Last year, it's filled with Freeze12 twice. Each time it last several weeks.
This summer, it's converted to 134 and refilled twice, and it lasted several weeks each refilled. I finally decided to buy refill kit from Walmart and refill it myself several weeks each time.
Here the story begin. Each time I opened the lower pressure cap to refill, I see it's wet (2 or 3 times total this summer). I just clean it and refilled. Tonight, I opened it and see it completely filled with fluid (conentrated bubbles). It alarmed me that something is wrong. Maybe here is the leak which I should be looking for? I then opened the high pressure valve and push on the pin to see if it still has any pressure. Yes, it's very strong. Meaning the system still have a lot of pressure, at least on the high pressure side.
Then I begin my refill process as normal hoping to get through the rest of the summer. On the lower side, the Walmart gauge showed almost empty. After pumping more than 1/2 of the big bottle (~$10 bottle), I took it off and get into the car to see if it's any colder, no it's not. After turning off the car and heard a lound hissing sound. It turned out that the lower valve (where I pumped) is leaking bad. I leaked out the concentrated bubbles type of fluid. At this point, I just stood there and watch. After couple seconds, I decided to put the cap on even it's still leaking. Then it's stoped leaking while the cap was scewing on and AC is still not cold.
Again, I opened the high side and push the pin to see if there is any pressure left, yes, still lot of pressure.
Anyone know what is going on? Is it simply the lower valve is bad/leaking or is it because I over filled it and the valve is smart enough to open itself to let the fluid out? Or is there something is bad in the system that make the lower side is too lowed but the high side is still full? Is there a valve between lower and higher side, which is bad?
Anyone can give me any suggestion? I just don't want to bring it to the shop to spend a bunch of $$ while it might be something simple that I don't know yet.
Thank you.

You need to fix the leak and stop wasting freon (1) it's VERY bad for the enviroment (2) it's costly. I would replace the schrader valves in the high and low presure side service ports, then have the system vacumed down and leak checked. It sounds like you have air and moisture in the system this is not good. If you don't have a vacum pump and the proper tools PLEASE TAKE IT TO SOMEONE and stop letting freon into the open air!!!!!!!!! Also go to an autoparts store and get a Haynes manual about A/C systems this will be a good sorce to answer alot of questions

Assuming that you have the stock York compressor you need to replace the rotolock valves before you waste more freon on this endevour. Griffiths has them in stock, they come with new flange gaskets and o-rings, however I recommend you source the teflon o-rings as well to "update" the fitting.

You see, there is a teflon stem gasket inside the service valve that deteriorates over time. Since they sit in one position for the vast majority of their lives they just break down over time. People have attempted to replace the teflon stem, but it's dicey, so just get yourself a new set.

Thanks guys. This is the seocnd time I feel sick about my AC. I will either bring it to another shop or just forget about AC (again). But just to understand, the valves are new. The shop converted them not too long ago this summer, for 134. And when I bought more 134, I also got several more of these valves.
Thanks for opinion.

You have several sets of backseat valves? That's a rather large expense. Or are you talking about the schrader valve inside the backseat valve? Also are you using them correctly? All the way clockwise is closed.

no no, not the expensive valves. The one you add to the stock valves to fit the 134 fitting. On the pics., what I was talking about is the two with blue and red caps.
I didn'tn install them myself. The shop did, although I don't think it's that complicated.
http://www.griffiths.com/porsche/ac/911ac/R134akit1.gif

Yea, they just screw on. The strange thing here is that if your service valves are working correctly, they should be stopping the leak before the add-on 134 fittings. You are closing the backseat valves after charging, correct?

base on what you are saying, I guess the backseat valve is a manual valve which I can open and close manually, in front of this adapter. I don't have this manual valve.
The stock compressor doesn't come with this valve. When the tech install this adapter (with the pic/core inside) I think he took out the pin/core inside the stock opening. So this valve/adapter is the only thing left on there to close it.

Oh crap, you have an 87, that's a DENSO compressor. Interesting that the tech removed the original cores, normally you just screw the 134 fittings over the original cores. I have seen a ton of these cheap 134a retro fittings leaking, in fact I have seen a few that were cracked even. I know there are higher quality metal retro fittings available, however many folks use the inexpensive plastic ones.

Mine were aluminum. Should I asked for metal instead of aluminum next time?

I am almost afraid of adding to this confusion, but I had a similar experience this summer with my '87 still running R-12. I have had a consistent slow leak for the last two summers. In June of this year I took the car in for a conversion. When we took off the cap on the low side I also found bubbles. The shop suggested that instead of major work that we simply replace the Schrader valves, pull a vacuum and refill. I'm still getting cold (everything is relative!) air and I'm surviving an East Texas summer for a $0.39 valve!!

I think AL's are the good ones, I'm surprised that they failed in fact. Those are far better than the plastic ones. Llike the poster below you should probably replace the cores, the tool is like $2 and the valves are pennies.

ned903,
sounds like similar problem, just the diff. is I am having 134 now. Lucky you. I have visited the shop for this AC thing several times a year. To the point I have decided to ditch the AC already but every summer, reading someone work on this board, I am back to the original spot again.
Thanks

Scott R,
Thanks again for ideas. I got all the answers and will try it again. Hopefully this is the last time I have to do something with my AC and it will run "perfect" :)

Again, thanks all.

Aluminium is metal, it turns out. as opposed to plastic.

Do you think that there is some Freeze 12 still in there? 134a now?

If you're using the kits with oil in them, you may have too much oil in the system (you said it was 'wet')?

You probably can't pull enough vacuum at home.

icar,
I did not do it at home. All those services of recharging with Freeze12, converting to 134 and recharges several times were done at the shop (not by me). After all those services, I still feel like it's leaking somewhere because cold air reduced after several weeks each recharge, then I decided to do the recharge myself, several times recently. Then, I see the low side cap is wet then leak, etc...

I didn't have a chance to bring it in to replace the valve yet but on the drive tonight, my cabin was completely cold. Al I did was windows wide open, AC turn off :lol: