Upon arrival to system no cool, I was shown to a thermostat on the wall that wasn’t operating at all. Immediately pulled thermostat off the wall and tried to bypass to get the system started and everything would run except the outdoor C/U in the cooling mode. Upon further inspection I found loss of power between the low voltage wiring in the system for the outdoor C/U. I was losing power once it left the A/H to the C/U. Checked all wiring and when I went to unwrap the condenser wiring I pulled a wire straight off that was barely attached. Respliced and repaired wiring then put power back to the system. I now had correct power and the system would start if the thermostat was bypassed. This thermostat has failed due to a low voltage short that was happening intermittently due to the loose wiring connections. Replaced and wired thermostat and started the system in the cooling mode. System is now operating normally in the cooling mode. I did notice the systems drain line was clogge