A year ago my mechanic flushed and rebuilt my AC system, new comp, shearer valves, expansion valve, receiver dryer, O rings, and flushed everything. Vacuumed it down and it held no prob for 15 min. 2 weeks later, my AC was low on charge.

Just sent leak hunting tonight. Put 65 psi of compressed air in the system (yes, I know, this is a no no”. A few hrs later it sunk to 60 psi.

Finally traced it back to a slow leak at the expansion valve. Foam on the piping around it was soaked in oil. Obviously the system slowly vented through there.

How much oil am I supposed to add??? I’m not sure how much leaked out, but it doesn’t look like much