Tech found 2015 model Trane split system (last 4 of outdoor unit R34F) not cooling due to a failed 7.5uf outdoor fan capacitor. Tech replaced it for testing and found outdoor fan back amping correctly and system cooling correctly. TXV was replaced and leak repaired on this system in September last year. System is back cooling normally. Tech found 2014 model Trane split system (last 4 of outdoor unit RG4F) not cooling due to being nearly devoid of 9 lbs of R410a. Had about 80 psi of standing pressure, but low pressure switch was stuck open. High pressure switch was closed. Tech bypassed low pressure switch to get system to start up for testing, but compressor made a grinding sound and did not start. Capacitor is within specs. Tech homed compressor, but it still will not start. Tech diagnosed failed low pressure switch, failed compressor, major refrigerant leak or leaks in system holding 10 lbs R410a. Outdoor unit is highly corroded. Tech recommends system replacement. Lanie approved c