Please excuse my newness. My mechanic has replaced a dead compressor and dryer and converted to the newer freon (134a?). He has recharged the system 2 or 3 times now and used the freon sniffer and added dye to find the leak. It's stops working after 24 hours after a recharge. My AC system is leaking, but where. I've got a lot of money tied up in this effort and I'm wondering if throwing more money at the beast will solve the problem. Could it be on the low pressure side since it takes a while to leak out. It doesn't all leak out, just enough to keep the compressor from working. Are there weak spots in the AC system that are common to the 1990 LS400? Please help, he is ready to tear into the dash.