Customer was notified yesterday that the system is low on R-22 refrigerant. After leaving yesterday the system ran for a while and then shut off after a few hours. Technician believes that the evaporator coil is freezing up and is causing the suction pressure to drop enough to shut the system down on low pressure. Performed a leak search but was unable to definitively find a leak as this leak detector is not made to find R-22 refrigerant. There is water damage inside the air handler and the emergency drain pan is very corroded from long term water damage. These are signs that the coil has been freezing and thawing for a quite some time. Drain lines are clear. Comfort advisor is scheduled to meet with the customer this evening between 6-8pm. If comfort advisor could please call Mark D before running this call it would be appreciated.