Carrier PG8JEA Installation, Start-up, Operating And Service And Maintenance Instructions

46gized 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 startthe 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. Humidity Sensing Thermostat Mode(See Fig. 26 -- 29 for humidity sensing thermostat connec-tions.)The dehumidification output, DHUM on the humiditysensing thermostat should be connected to the furnacecontrol thermostat terminal DHUM. When there is a dehu-midify demand, the DHUM input is activated, whichmeans 24 vac signal is removed from the DHUM inputterminal. In other words, the DHUM input logic is re-versed. The DHUM input is turned ON when no dehumid-ify demand exists. Once 24 vac is detected by the furnacecontrol on the DHUM input, the furnace control operatesin humidity sensing thermostat mode. If the DHUM inputis low for more than 48 hours, the furnace control revertsback to non--humidity sensing thermostat mode.The cooling operation described in item 2. above also ap-plies to operation with a humidity sensing thermostat. Theexceptions are listed 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 thePG8MEA