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

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50the furnace blower motor BLWM on COOL speed.The electronic air cleaner terminal EAC--1 is energizedwith 115 vac whenever the blower motor BLWM is oper-ating.When the thermostat is satisfied, the R--to--G--and--Y1 orR--to--G--and--Y1 and Y2 circuits are opened. The out-door unit stops, and the furnace blower BLWM and elec-tronic air cleaner terminal EAC--1 will remain energizedfor an additional 90 seconds. Jumper Y1 to DHUM to re-duce the cooling off--delay to 5 seconds. (See Fig. 24.)3. Thermidistat Mode(See Fig. 26--29 for Thermidistat connections.)The dehumidification output, DHUM on the Thermidistatshould be connected to the furnace control thermostat ter-minal DHUM. When there is a dehumidify demand, theDHUM input is activated, which means 24 vac signal isremoved from the DHUM input terminal. In other words,the DHUM input logic is reversed. The DHUM input isturned ON when no dehumidify demand exists. Once 24vac is detected by the furnace control on the DHUM input,the furnace control operates in Thermidistat mode. If theDHUM input is low for more than 48 hours, the furnacecontrol reverts back to non--Thermidistat mode.The cooling operation described in item 2. above also ap-plies to operation with a Thermidistat. The exceptions arelisted below:a. When the R--to--G--and--Y1 circuit is closed and there isa demand for dehumidification, the furnace blower motorBLWM will continue running at low--cool speed (samespeed as FAN).b. When the R--to--G--and--Y/Y2 circuit is closed and thereis a demand for dehumidification, the furnace blower mo-tor BLWM will drop the blower speed from COOL toHEAT for a maximum of 10 minutes before revertingback to COOL speed. If there is still a demand for dehu-midification after 20 minutes, the furnace control CPUwill drop the blower speed back to HEAT speed. This al-ternating 10-- minute cycle will continue as long as thereis a call for cooling.c. When the “call for cooling” is satisfied and there is a de-mand for dehumidification, the cooling blower--off delayis decreased from 90 seconds to 5 seconds.4. Continuous Blower ModeWhen the R--to--G circuit is closed by the thermostat, theblower motor BLWM will operate on continuous--blowerspeed (can be adjusted to FAN, HEAT, or COOL speed) atthe thermostat. Factory default is FAN speed. TerminalEAC--1 is energized as long as the blower motor BLWM isenergized. During a call for heat, the blower BLWM willstop during igniter warm--up (17 seconds), ignition (7seconds), and blower--ON delay (25 seconds), allowingthe furnace heat exchangers to heat up more quickly, thenrestarts at the end of the blower--ON delay period at HEATspeed.In heating, the furnace control CPU will hold the blowermotor BLWM at HEAT speed during the selected blower--OFF delay period before reverting to continuous--blowerspeed. When the thermostat “calls for low--cooling,” theblower motor BLWM will switch to operate at low--coolspeed (same speed as FAN). When the thermostat is satis-fied, the blower motor BLWM will operate an additional90 seconds on low--cool speed (same speed as FAN) be-fore reverting back to continuous--blower speed.When the thermostat “calls for high--cooling”, the blowermotor BLWM will operate at COOL speed. When thethermostat is satisfied, the blower motor BLWM will oper-ate an additional 90 seconds on COOL speed before re-verting back to continuous--blower speed.When the R--to--G circuit is opened, the blower motorBLWM will continue operating for an additional 5seconds, if no other function requires blower motorBLWM operation.Continuous Blower Speed Selection from Thermostat--To select different continuous--blower speeds from theroom thermostat, momentarily turn off the FAN switch orpush button on the room thermostat for 1--3 seconds afterthe blower motor BLWM is operating. The furnace controlCPU will shift the continuous--blower speed from the fact-ory setting of FAN to HEAT speed. Momentarily turningoff the FAN switch again at the thermostat will shift thecontinuous--blower speed from HEAT to COOL. Repeat-ing the procedure will shift the continuous--blower speedfrom COOL to FAN speed. The selection can be changedas many times as desired and is stored in the memory to beautomatically used following a power interruption.5. Heat pump(See Fig. 28-- 31 for thermostat connections.) When in-stalled with a heat pump, the furnace control automaticallychanges the timing sequence to avoid long blower offtimes during demand defrost cycles. When the R--to--W--and--Y1 or R--to--W--and--Y1--and--G circuits are ener-gized the furnace control CPU will switch to or turn on theblower motor BLWM at HEAT speed, and begin a heatingcycle. The blower motor BLWM will remain on until theend of the prepurge period, then shut off for 24 secondsthen come back on at HEAT speed. When the W input sig-nal disappears, the furnace control begins a normal inducerpost--purge period and the blower remains running atHEAT speed for the selected blower--OFF delay periodthen switches to low--cool speed (same speed as FAN). Ifthe R--to--W--and--Y1--and--G signals disappear at thesame time, the blower motor BLWM will remain on forthe selected blower--OFF delay period. If the R--to--W--and--Y1 signals disappear, leaving the G signal, theblower motor BLWM will remain on for the selectedblower--OFF delay period then switch to continuous--blowerspeed. When the R--to--W--and--Y/Y2, R--to--W--and--Y/Y2--and--G, R--to-- W--and--Y1--and--Y/Y2, or R--to--W--and--Y1--and--Y/Y2--and--G circuits are energized thefurnace control CPU will switch to or turn on the blowermotor BLWM at HEAT speed, and begin a heating cycle.The blower motor BLWM will remain on until the end ofthe prepurge period, then shut off for 24 seconds thencome back on at HEAT speed. When the W input signaldisappears, the furnace control begins a normal inducerpost--purge period and the blower switches to COOLspeed after a 3 second delay. If the R--to--W--and--Y/Y2--and--G or R--to--W--and--Y1--and--Y/Y2--and--Gsignals disappear at the same time, the blower motorBLWM will remain on for the selected blower--OFF delayperiod. If the R--to--W--and--Y/Y2 or R--to--W--and--Y1--and--Y/Y2 signals disappear, leaving the G signal, theblower motor BLWM will remain on for the selectedblower--OFF delay period then switch to continuousblower speed.Wiring DiagramsRefer to Fig. 54 for wiring diagram.TroubleshootingRefer to the service label (See Fig. 50). The TroubleshootingGuide (See Fig. 55) can be a useful tool in isolating furnaceoperation problems. Beginning with the word “Start,” answereach question and follow the appropriate arrow to the next item.The Guide will help to identify the problem or failed component.After replacing any component, verify correct operationsequence.58DL