Upon arrival, client was not on site. Had instructions to begin diagnostic without her. Call was for upstairs system. Found condenser and it was running. Checked charge and it was flat on refrigerant. System runs on R22 which is outdated and no longer manufactured. Because of that repair cost is high. Was unable to pin point where leak I’d coming from. High chance it’s in the condenser because of oil stains on unit. Informed,Ed client of findings. Went over repair options. Have follow up call on Monday may second to go over findings. Left system off at breaker upon departure.