If the pressure line (high side, between compressor and condenser) service port had a faulty valve and leaks, how long would it take for the system to leak enough out for the AC to not cool any longer?

I have a leak and I have been fighting with my high side service port trying to stop the leak and I vacuumed it down Friday morning and it held vacuum for 30 mins. I charged the system up and used it friday, saturday, and then today I go to use it and its blowing cool but not cold, the suction line after the STV is frosting up telling me that I am about 24 oz low on refrigerant. I hate to break every connection loose just to change all the O-rings if this leak can be accelerated by a faulty high pressure service port when its being used. Ive done changed the core with 6 different ones, it wouldnt seal. So I bought a R-12 to R-134a adapter with its own valve and even that doesnt seal the valve is leaking pressure out and I am at the point I will have to take this line off and have one made but I am tired of putting money at it trying to fix it if the symptons of how quick it goes down might be signs of a bigger problem.

For instance I am told by some that my condenser or my evaporator or even my hoses could be leaking. I am not sure but I think in that case the pressure would go down a lot quicker than it is. Plus it doesnt jive with the fact I was able to get it to hold vacuum for 30 mins without a change in the gauges. Only after I charged the system up did I noticed my high pressure service port valve was bubbling small bubbles telling me that still hasnt been fixed.



Aside from that does anyone know where to get OEM premade A/C hoses with the crimped fittings for the older cars? Rock auto doesnt sell hoses for mine and I hate to drive around with my system open to the moisture and dirt and grime just to have a new hose made.



Update

Well I checked it I had 250 high side and 35 low side when I charged it up friday. I hooked gauges up and I was at 200 high 30 low so didnt lose too much as I suspected. I checked the high pressure port with water and it wasnt bubbling. I charged it up and then thats when I noticed when running it was a slow leak through the service port. I got it tightened down more and I think I stopped it but cant tell since I didnt rev the engine up to simulate driving conditions. I wont go tighter on the shradervalve cause Ive broken too many of them trying to stop the high side leak before I went to the R134a adapter service port.

 

If you have a proper cap with a good seal, a small leak at the service port valve is not an issue, The cap is actually the primary seal on R134a service ports.

As far as how much will leak from a articular place, there's absolutely no way to tell.

The only way you are going to solve your problem is to find and fix ALL of the leaks.

 

I am 99.9% sure there is only one leak. Seeing as none of the other connection points or fittings have any oily residue indicating a refrigerant leak I am betting its the valve. I got it tight enough I think its not leaking when the system is running but its hard to tell with the fan blowing the water out. I think I will just have to see if it lasts longer than 3 days, if its like it was when I first serviced the car when I got it back in 06 and I only have to add half a can every season to every other season then I am set. If not I will just have to break down and have a new pressure line made.

 

Along with a high quality or new cap the Schraeder valves should be replaced too. While the caps are indeed the primary sealing device it doesn't hurt to keep the pressure inside the system as much as possible.

 

Holding in vaccum can only be judged properly by way of microns. You need a micron gauge to determine how low it actually goes and then if it stays.

In residenatial air conditioning systems we go down to 500 microns. As the lines stabilize, once the vacuum is stopped, the micron level rises and then settles. If it rises to above 1000 microns than most likely there is a leak. We leave the micron gauge on the system after a vaccum for around an hour.

That's one way to determine if there's a leak. The other is a nitrogen pressure test.

As for your shraeder valves, replace them both regardless of if needed and get some metal threaded caps and screw them down onto the ports. Take the ones from your home's condenser if you need to but only if you're certain there is no leak there.

Many times that's all it takes, a cap tightened down.