Returned to diagnose 2 RTUs. Front system #1 is operating properly upon thermostat call, proper delta T is acquired. Belt is tight up to specs, no abnormal noise was detected throughout visit. System #2 (middle) has a shorted 2 pole compressor contactor, the reason for the transformer to trip upon a Y( compressor) call. Tech was unable to contact kris. Bruce approved the repairs for system #2. Tested system In cooling from the thermostat and both compressors operated properly. System is back cooling.