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

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Carrier 58DLA Installation, Start-up, Operating And Service And Maintenance Instructions Manual pdf 49 page image

49A91252Fig. 53 -- Cleaning Heat Exchanger Cell14. Reinstall internal vent pipe, if applicable.15. Reinstall vent connector on furnace vent elbow. Securelyfasten vent connector to vent elbow with 2 field--supplied,corrosion--resistant, sheet metal screws located 180_ apart.16. Replace blower access door only, if it was removed.17. Set thermostat above room temperature and check furnacefor proper operation.18. Verify blower airflow and speed changes between heatingand cooling.19. Check for gas leaks.20. Replace outer access door.FIRE OR EXPLOSION HAZARDFailure to follow this warning could result in personal injury,death and/or property damage.Never test for gas leaks with an open flame. Use acommercially available soap solution made specifically forthe detection of leaks to check all connections.! WARNINGSequence of OperationNOTE: Furnace control must be grounded for proper operationor control will lock out. Control is grounded throughgreen/yellow wire routed to gas valve and manifold bracketscrew. Using the schematic diagram in Fig. 51, follow thesequence of operation through the different modes. Read andfollow the wiring diagram very carefully.NOTE: If a power interruption occurs during a call for heat (W),the control will start a 90--second blower--only ON period twoseconds after power is restored, if the thermostat is still calling forgas heating. The Amber LED light will flash code 12 during the90--second period, after which the LED will be ON continuous,as long as no faults are detected. After the 90--second period, thefurnace will respond to the thermostat normally.The blower door must be installed for power to be conductedthrough the blower door interlock switch ILK to the furnacecontrol CPU, transformer TRAN, inducer motor IDM, blowermotor BLWM, hot--surface igniter HSI, and gas valve GV.1. Heating(See Fig. 25 for thermostat connections.)The wall thermostat “calls for heat,” closing the R--to--Wcircuit. The furnace control performs a self--check, verifiesthe pressure switch contacts PRS are open, and starts theinducer motor IDM.a. Inducer Prepurge Period-- As the inducer motor IDMcomes up to speed, the pressure switch contacts PRS closeto begin a 15--second prepurge period.b. Igniter Warm--Up-- At the end of the prepurge period,the Hot--Surface igniter HSI is energized for a 17--secondigniter warm--up period.c. Trial--for--Ignition Sequence-- When the igniter warm--up period is completed, the main gas valve relay contactsGVR close to energize the gas valve GV, the gas valveopens, and 24 vac power is supplied for a field--installedhumidifier at the HUM terminal. The gas valve GV per-mits gas flow to the burners where it is ignited by the HSI.Five seconds after the GVR closes, a 2--second flameproving period begins. The HSI igniter will remain ener-gized until the flame is sensed or until the 2--second flameproving period begins.d. Flame--Proving-- When the burner flame is proved at theflame--proving sensor electrode FSE, the furnace controlCPU begins the blower--ON delay period and continuesto hold the gas valve GV open. If the burner flame is notproved within two seconds, the control CPU will closethe gas valve GV, and the control CPU will repeat the ig-nition sequence for up to three more Trials--For--Ignitionbefore going to Ignition--Lockout. Lockout will be resetautomatically after three hours or by momentarily inter-rupting 115 vac power to the furnace, or by interrupting24 vac power at SEC1 or SEC2 to the furnace controlCPU (not at W, G, R, etc.).If flame is proved when flame should not be present, thefurnace control CPU will lock out of Gas--Heating modeand operate the inducer motor IDM until flame is nolonger proved.e. Blower--On Delay-- If the burner flame is proven, theblower motor is energized on HEAT speed 25 secondsafter the gas valve GV is energized.Simultaneously, the electronic air cleaner terminalEAC--1 is energized and remains energized as long as theblower motor BLWM is energized.f. Blower--Off Delay-- When the thermostat is satisfied, theR--to--W circuit is opened, de--energizing the gas valveGV, stopping gas flow to the burners, and de--energizingthe humidifier terminal HUM. The inducer motor IDMwill remain energized for a 5--second post--purge period.The blower motor BLWM and air cleaner terminalEAC--1 will remain energized for 90, 120, 150, or 180seconds (depending on the blower--OFF delay selection).The furnace control CPU is factory--set for a 120--secondblower--OFF delay.2. Cooling ModeThe thermostat “calls for cooling.”a. Single--Speed Cooling(See Fig. 25 -- 32 for thermostat connections)The thermostat closes the R--to--G--and--Y circuits. TheR--to-- Y circuit starts the outdoor unit, and the R--to--G--and--Y/Y2 circuits start the furnace blower motorBLWM on COOL speed.The electronic air cleaner terminal EAC--1 is energizedwith 115 vac when the blower motor BLWM is operating.When the thermostat is satisfied, the R--to--G--and--Y cir-cuits are opened. The outdoor unit will stop, and the fur-nace blower motor BLWM will continue operating on theCOOL speed for an additional 90 seconds. Jumper Y/Y2to DHUM to reduce the cooling off--delay to 5 seconds.(See Fig. 24.)b. Two--Speed Cooling(See Fig. 25--32 for thermostat connections.)The thermostat closes the R--to--G--and--Y1 circuits forlow--cooling or closes the R--to--G--and--Y1--and--Y2 cir-cuits for high--cooling. The R--to--Y1 circuit starts theoutdoor unit on low--cooling speed, and the R--to--G--and--Y1 circuit starts the furnace blower motorBLWM on low--cool speed (same speed as FAN). TheR--to--Y1--and--Y2 circuits start the outdoor unit on high--cooling speed, and the R--to--G and-- Y/Y2 circuits start58DL