It still showed about 20 psi on the system before i filled it. Before it started raining, i got my yellow glasses and UV lights and saw green dye on the underside of the compressor, a tiny amount on the hi and low fittings and little green flecks on the condenser. I will take some pictures.
I’m impressed you’re attempting to photograph the black light fluorescence. I’d have assumed that needs special filters.
From the description I’d guess the fittings show dye from when the gauges are attached and removed.
The condenser isn’t certain, some bug splat and other debris fluoresces. If there’s also or exclusively fluorescence that’s not the exact same color as the dye, or if you don’t see anything on the fan blades and fairing, then it’s very unlikely to be leaking at all. If you had seen patches or spots rather than flecks, or there was dye on the fan or fairing, I’d suspect the condenser was losing refrigerant.
Assuming the compressor isn’t just showing material that was ejected from the condenser and landed on it (the fan etc would also show it), then the questions are;
1) Are the line fittings leaking at the compressor? The car’s old enough for the o-rings to have failed.
2) Is the leakage from the shaft? It’s possible that the shaft seals leak at zero pressure and it’s meaningless, but it could be a pressure leak.
The 20psi residual pressure you found is well below the vapor pressure of R134a refrigerant at any temperature most people think of their A/C. There may be a small residue of refrigerant dissolved in the compressor oil that’s a source for a dwindling leak. You may be measuring the vapor pressure of a minor constituent or contaminant - a tiny amount of solvent added to improve solubility of PAG oil to improve oil return, or an oil intended to swell o-rings in a leak-stop.
If the charge was lost at the compressor fitting or shaft definintely find out how to get the oil level in the compressor right. There’s always a way, even it it’s flush it out with compressed gas and add X ounces. As mentioned before, change the filter dryer.
If you don’t see anything elsewhere on the lines, and nothing where the condensation drips, then I’d replace the o-rings in the line set connections, and while it’s at zero pressure I’d change every other line set connection o-ring I could reach without taking the dashboard apart. Then I’d clean up the compressor, and every other connection and then add just enough gas to make it leak if it plans to, say 40psi. You can use R134a, Nitrogen, CO2, Argon, almost anything is fine that’s lawful to use as long as it’s dry and oxygen free and you remove all of it before you refill the system. I wouldn’t use propane though, whatever other considerations apply, the job is enough to to without smell of mercaptan.
If you don’t see any more leaking, then pull a vacuum and dry the system out. If it’s not leaking you may need to run the pump for an hour or 4 to dry it or trapped water and refrigerant dissolved in oil everywhere in the system will vaporize and look like a leak. If you can close it off and it’s still in a deep vacuum the next day, fill it , look for leaks, test it, and look for leaks one last time.
Since it snowed yesterday, I hit "pause" on the AC troubleshooting.
