Performed system maintenance. Found system #2 low on refrigerant approximately 2 - 3 lbs 410a. Thermostat wire is damaged/frayed with copper wires showing. This can result in low voltage short further damage. Disconnect box for system #2 also damaged. Appears the copper connection has welded itself stuck. System #1 also operating with low refrigerant charge. Approximately 2 -3 lbs low r410a. Performed leak search as part of maintenance with no apparent leaks found during the time of the visit. Was some oil residue on first floor evaporator coil, but did not find apparent leak with electronic leak detector.