Recommendations is to do a total RTU replacement. Brand of unit American standard Model: WSC060A3RGA170001A1B000 Here are the steps of the installation 1. Power down the unit. And lock and tag the breaker. 2. Disconnect power at the unit 3. Disconnect control voltage to the unit 4. Disconnect drain lines to the system 5. Disconnect ductwork to the system. 6. Crane will arrive on site and set up for safety points 7. Remove old unit off roof 8. Replace the curb on top of the roof to be able to set new unit on 9. Secured curb to the roof, seal it all the joints connections to prevent any air leakages 10. Crane will lift new unit to the roof and set on curb adapter 11. Will secure the unit to the curb and make all the connections for the ductwork PVC drain lines power controls. 12. Will verify all components are in place and remove any shipping connectors to the system 13. Thermostat will be replaced with a Honeywell T6 14. Will start up unit and test the cooling mode a