Performed Maintenance on a pair of package units. Downstairs unit is non operational. Realtor told me to get it up and running. Replaced high voltage disconnect which was missing parts that it needs to function. Rewired low voltage at board and thermostat. Battery cap is low. Fan is spinning badly. Upstairs unit is vibrating significantly. Thus unit needs a new fan. Amperages are ok. Both package units are wired into the same breaker, this is against code. Systems are operational. Replaced high voltage disconnect that was corroded and missing pieces causing unit to get zero power. Rewired low voltage system in order to function properly.