Performed ac diagnostic found system not working, went thru inside unit upflow, in walk in off garage. Outside condenser out back, found blue pool trap on top of condenser. Txv build uninsulated under house. Outside was getting pressure switch error per control board, 5 flashes. Tested pressure switches high ok low not sending signal, went thru and verified there signal was right. Then tested refrigerant, zero pressure. We lost 12 lbs of r22 refrigerant. And now need to find the leak. My recommendation would be to pressure test system, to see if we have any major leaks, Due to age and shape don’t recommend putting that much money into repairs. Won’t get a return on investment. Client wants to see if he can get the r22 from a friend Go thru system to see what is happening