Carrier 59SC2C Series Installation, Start-up, Operating And Service And Maintenance Instructions

Also see for 59SC2B: Product data

67Adjust Cooling AirflowThe cooling airflow can be set from the remaining blower speedtaps. Refer to the Air Delivery Tables in these instructions.FURNACE OVERHEATING HAZARDFailure to follow this caution may result in reduced furnacelife.Recheck temperature rise. It must be within limits specifiedon the rating plate. Recommended operation is at themid--point of rise range or slightly above.CAUTION!Adjust Thermostat Heat AnticipatorMechanical thermostat: Set thermostat heat anticipator to matchthe amp draw of the electrical components in the R--W circuit.Accurate amp draw readings can be obtained at the wires normallyconnected to thermostat subbase terminals R and W. Thethermostat anticipator should NOT be in the circuit whilemeasuring current.1. Remove thermostat from subbase or from wall.2. Connect an amp meter across the R and W subbase termin-als or R and W wires at wall.3. Record amp draw across terminals when furnace is in lowheat and after blower starts.4. Set heat anticipator on thermostat per thermostat instruc-tions and install on subbase or wall.5. Install blower access door.Electronic thermostat: Set cycle rate for 3 cycles per hr.Check Safety ControlsThe flame sensor, gas valve, and pressure switch were all checkedin the Start--up procedure section as part of normal operation.1. Check Main Limit SwitchThis control shuts off combustion system and energizes air--circulating blower motor, if furnace overheats. By using thismethod to check the temperature limit control, it can be es-tablished that the limit is functioning properly and that thelimit will operate if there is a restricted return--air supply ormotor failure. If the limit control does not function duringthis test, the cause must be determined and corrected.a. Run furnace for at least 5 minutes.b. Gradually block off return air with a piece of cardboard orsheet metal until the limit trips.c. Unblock return air to permit normal circulation.d. Burners will re--light when furnace cools down.2. Check Pressure Switch(es)This control proves operation of the draft inducer blower.a. Turn off 115--v power to furnace.b. Disconnect inducer motor lead wires from wire harness.c. Turn on 115--v power to furnace.d. Set thermostat to “call for heat” and wait 1 minute. Whenpressure switch is functioning properly, hot surface ignitershould NOT glow and control diagnostic light flashes astatus code 31. If hot surface igniter glows when inducermotor is disconnected, shut down furnace immediately.e. Determine reason low pressure switch did not functionproperly and correct condition.f. Turn off 115--v power to furnace.g. Reconnect inducer motor wires, replace outer door, andturn on 115--v power.h. Blower will run for 90 sec before beginning the call forheat again.i. Furnace should ignite normally.Checklist1. Put away tools and instruments. Clean up debris.2. Verify that the jumper is removed from the TEST/TWINterminal. Verify that there is nothing plugged into the PLTconnector. (Note: If there is a jumper connector pluggedinto PLT, remove it and discard.) See Fig. 38.3. Verify that the Blower/Heat Off Delay jumpers are set asdesired. See Fig. 38 and 70.4. Verify that the blower (lower door in upflow position) andcontrol (“Main” or upper door in upflow position) doors areproperly installed.5. Verify that the Status LED glows. If not, check that thepower supply is energized and that the blower door issecure. See Fig. 61 to interpret diagnostic codes.6. Cycle test furnace with room thermostat to be sure that itoperates properly with the room thermostat. Check allmodes including Heat, Cool and Fan.7. Check operation of accessories per manufacturer’sinstructions.8. Review Owner’s Manual with owner.9. Attach entire literature packet to furnace.59SC2C