When I got it years ago it was not cold. I charged it and it was ice cold. Last year it was getting warmer so I used part if a 12oz can of AutoZone R134a with stop leak and it got colder again. This year it is warm air. That can from last year doesn't seem to want to fill the system. I got a new taller can with new filler attachment and it all went in and the system got cool but not cold. The system seems to be working intermittently. Sometimes the air is cool and other times it isn't. Not quite as warm as outside but not cool.
Any ideas before I crack the new can of stop leak with dye and the new UV light?
Not knowing much more than what I saw on yt of a compressor replacement and system charge, and what I thought coming home from buying the uv light it seems like it might be something mechanical.

 

Need to see what pressure is doing when the system is running..... If your can has a gauge with it, there should also be a chart that tells you what low side pressure should be, for a given temp. (outside temp)

 

OK in a bit I'll try to work out why the old gauge didn't let the can empty. the AZ girl seemed to think it was clogged by the stop leak.
Then if that doesn't work I'll try the new one (AC Pro) and a new can of no dye R134a to find out what the pressure is and get back to ya.

 

OK ran it 5 minutes. The compressor went on for a count of 15 and then off for a count of 10, over and over. Ambient temp is 80 the temp in the left center outlet is 60. The gauge on the old one went up to 45 while the compressor was on then down to 25 (or possibly the reverse):/. The hard hose with the connector in it was cold and starting to sweat.
the chart says at 80 pressure should be 40-50. https://rechargeac.com/how-to/ac-system-pressure-chart

 

Pressure on the low side should go down when the compressor is running. If it drops below the shutoff pressure, the compressor clutch will disengage. (and then pressure will come back up) Given your conditions, low side pressure (what the gauge can is reading) should be in the 40-50 range while the compressor is running. If it isn't, then you are low on refrigerant.

 

With all the refrigerant that has been added in the short timeframe there has got to be a leak somewheres.

 

OK I used the AC Pro connector and got most of the 3oz can of stop leak with leak detector into the line. It seems like it is running a few more seconds before kicking off. It had a red dye. The AC Pro gauge is digital and it felt like it wasn't working well. The numbers it showed were way different from the gauge in the blue AZ short hosed filler.
I looked at that video linked at top then checked what my static pressure was on the blue short lined Auto Zone filler tube with gauge after adding the stop leak/dye. It lines up between the 55 and 100, there is no smaller gradation in that area, closer to the 55 which I figure to be >65 which is what the chart I found says should be for 68 ambient temp. https://ricksfreeautorepairadvice.co...ssure-reading/
I tried to add more off the 12oz can of AZ that would not empty with no joy. I stuck my hand in front of the vent and it was cold. The blue gauge did cycle between the two red lines with the ambient temp in middle while I had it hooked up trying to fill. I am hesitant to try to add more right now.
So it seems like it is colder now but that could be just because it is not so freaking hot out. I hope that dye shows up the leak soon..