Tech found outdoor unit not running due to outdoor disconnect off (in the upside down position). Tech called for cooling upstairs and downstairs and found 45/5uf dual run capacitor has failed. Tech replaced dual run capacitor for testing. Zone system components are in upstairs closet. Bypass damper was set on middle static pressure setting (factory default) and remained closed even when only one zone was calling. Tech adjusted damper setting lower to ensure damper is fully closed when one zone is calling and partially open when only one zone is calling. Tech monitored system in cooling mode with both zones calling and only one zone calling. System stabilized in cooling mode. Compressor is making an odd pulsing/rumbling noise. Compressor is not overamping, refrigerant pressures look normal, and compressor windings Meg ohmed in the green. System is back cooling although compressor is noisy. Tech replaced dual run capacitor, adjusted bypass damper, and customer invested in PSA. Cust