Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for WeatherExpert 48N2: Installation instructions Installation instructions Controls, start-up, operation, service, and troubleshooting Installation instructions

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Carrier WeatherExpert 48N2 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 173 page image

173must then be manually reset by power down and power up ofthe unit.LIMIT SWITCH THERMISTOR (Staged Gas UnitOnly) — The limit switch thermistor is a factory-installedcomponent. It is located next to the lower limit switch. Thelimit switch thermistor senses temperature at limit switch loca-tion and prevents the limit from tripping while the unit is oper-ating at low airflow.PRESSURE SWITCH (Modulating Gas Units Only) —This switch senses vacuum to ensure the proper function ofcombustion induced-draft blower. It is a normally open switchset to close on negative pressure rise. The pressure switch islocated next to ignition and modulating gas controllers in thegas section.ROLLOUT SWITCH — This switch senses any flame or ex-cessive heat in the main burner compartment and deenergizesthe gas valve. If this occurs, the gas heating system is lockedout (7 flashes on IGC board) until the rollout switch is resetmanually. Reset rollout switch manually by powering downand powering up of the unit.When the rollout switch trips, it usually indicates a flueblockage. Inspect the unit for any obstruction in the flue sys-tem, for holes in the flue box, a defective hall effect sensor orpressure switch, a defective inducer motor, or a loose combus-tion blower.Compressor Removal — All compressors can be re-moved from the compressor side of the unit.1. Disconnect power to unit; lockout power to compressor.2. Close suction and discharge service valves.3. Relieve refrigerant pressure into a refrigerant recoverysystem.4. Disconnect power wires at terminal box and disconnectconduit.5. Disconnect wires from crankcase heater.6. Lift compressor off mounting bolts and remove.Compressor Replacement — Perform the following:1. Reverse procedure in Compressor Removal section.2. Leak-check and evacuate system, recover refrigerant.3. Recharge system per pre-start-up and start-up sequences.Recheck oil levels.4. Energize crankcase heater for 24 hours prior to restart ofsystem.IMPORTANT: All compressor mounting hardware andsupport brackets removed during servicing must be rein-stalled prior to start-up.