Carrier 58CVA Installation, Start-up, Operating And Service And Maintenance Instructions

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Carrier 58CVA Installation, Start-up, Operating And Service And Maintenance Instructions Manual pdf 47 page image

b. When the R to Y/Y2 circuit is closed, R to G circuit isopen, and there is a demand for dehumidification, thefurnace blower motor BLWM will drop the blower airflowto 65 percent of high-cooling airflow for a maximum of 10minutes each cooling cycle or until the R to G circuit closesor the demand for dehumidification is satisfied. High-cooling airflow is based on the A/C selection shown in Fig.55.c. When the ″call for cooling″ is satisfied and there is ademand for dehumidification, the cooling blower-off delayis decreased from 90 seconds to 5 seconds.6. Continuous Blower ModeWhen the R to G circuit is closed by the thermostat, the blowermotor BLWM will operate at continuous blower airflow.Continuous blower airflow selection is initially based on theCF selection shown in Fig. 55. Factory default is shown in Fig.55. Terminal EAC-1 is energized as long as the blower motorBLWM is energized.During a call for heat, the furnace control CPU will transitionthe blower motor BLWM to continuous blower airflow,low-heat airflow, or the midrange airflow, whichever islowest. The blower motor BLWM will remain ON until themain burners ignite then shut OFF and remain OFF for theblower-ON delay (45 seconds in low-heat, and 25 seconds inhigh-heat), allowing the furnace heat exchangers to heat upmore quickly, then restarts at the end of the blower-ON delayperiod at low-heat or high-heat airflow respectively.The blower motor BLWM will revert to continuous-blowerairflow after the heating cycle is completed. In high-heat, thefurnace control CPU will drop the blower motor BLWM tolow-heat airflow during the selected blower-OFF delay periodbefore transitioning to continuous-blower airflow.When the thermostat ″calls for low-cooling″, the blower motorBLWM will switch to operate at low-cooling airflow. Whenthe thermostat is satisfied, the blower motor BLWM willoperate an additional 90 seconds at low-cooling airflow beforetransitioning back to continuous-blower airflow.When the thermostat ″calls for high-cooling″, the blowermotor BLWM will operate at high cooling airflow. When thethermostat is satisfied, the blower motor BLWM will operatean additional 90 seconds at high-cooling airflow beforetransitioning back to continuous-blower airflow.When the R to G circuit is opened, the blower motor BLWMwill continue operating for an additional 5 seconds, if no otherfunction requires blower motor BLWM operation.Continuous Blower Speed Selection from Thermostat -Toselect different continuous-blower airflows from the roomthermostat, momentarily turn off the FAN switch or push-button on the room thermostat for 1-3 seconds after the blowermotor BLWM is operating. The furnace control CPU will shiftthe continuous-blower airflow from the factory setting to thenext highest CF selection airflow as shown in Fig. 55.Momentarily turning off the FAN switch again at the thermo-stat will shift the continuous-blower airflow up one moreincrement. If you repeat this procedure enough you willeventually shift the continuous-blower airflow to the lowestCF selection as shown in Table 1. The selection can bechanged as many times as desired and is stored in the memoryto be automatically used following a power interruption.7. Heat pumpSee Fig. 26-29 for thermostat connections.When installed with a heat pump, the furnace control auto-matically changes the timing sequence to avoid long bloweroff times during demand defrost cycles. Whenever W/W1 isenergized along with Y1 or Y/Y2, the furnace control CPUwill transition to or bring on the blower motor BLWM atcooling airflow, low-heat airflow, or the midrange airflow,whichever is lowest. The blower motor BLWM will remain onuntil the main burners ignite then shut OFF and remain OFFfor 25 seconds before coming back on at heating airflow.When the W/W1 input signal disappears, the furnace controlbegins a normal inducer post-purge period while changing theblower airflow. If Y/Y2 input is still energized the furnacecontrol CPU will transition the blower motor BLWM airflowto cooling airflow. If Y/Y2 input signal disappears and the Y1input is still energized the furnace control CPU will transitionthe blower motor BLWM to low-cooling airflow. If both theY1 and Y/Y2 signals disappear at the same time, the blowermotor BLWM will remain on at low-heat airflow for theselected blower-OFF delay period. At the end of the blower-OFF delay, the blower motor BLWM will shut OFF unless Gis still energized, in which case the blower motor BLWM willoperate at continuous blower airflow.8. Component testThe furnace features a component test system to help diagnosea system problem in the case of a component failure. Toinitiate the component test procedure, ensure that there are nothermostat inputs to the control and all time delays haveexpired. Turn on setup switch SW1-6. See Fig. 32.NOTE: The component test feature will not operate if the controlis receiving any thermostat signals or until all time delays haveexpired.The component test sequence is as follows:a. The furnace control CPU turns the inducer motor ON athigh-heat speed and keeps it ON through step c.b. After waiting 10 seconds the furnace control CPU turns thehot surface igniter ON for 15 seconds, then OFF.c. The furnace control CPU then turns the blower motorBLWM on at midrange airflow for 15 seconds, then OFF.d. After shutting the blower motor OFF the furnace controlCPU switches the inducer to low-heat speed for 10 sec-onds, then OFF.NOTE: The EAC terminals are energized when the blower isoperating.After the component test is completed , 1 or more status codes (11,25, or 41) will flash. See component test section or Service Label(Fig. 50.) for explanation of status codes.NOTE: To repeat component test, turn setup switch SW1-6 toOFF and then back ON.Step 4—Wiring DiagramRefer to wiring diagram Fig. 51.Step 5—TroubleshootingRefer to the service label. (See Fig. 50—Service Label.)The Troubleshooting Guide can be a useful tool in isolatingfurnace operation problems. Beginning with the word “Start,”answer each question and follow the appropriate arrow to the nextitem.The Guide will help to identify the problem or failed component.After replacing any component, verify correct operation sequence.A more detailed Troubleshooting Guide is available from yourdistributor.46