Sequence Of Operation; Heating Mode - Carrier weathermaker 8000 Installation, Start-Up And Operator's Manual

115-VAC (L1)
POWER
SUPPLY
Fig. 10—EAC Terminals on Control Board

SEQUENCE OF OPERATION

Furnace control must be grounded for proper operation, or
control will lockout. Control is grounded through green wire
routed to gas valve and burner bracket screw.
Using the schematic diagram shown in Fig. 11, follow the
sequence of operation through the different modes. Read and
follow the wiring diagram very carefully.
NOTE: If there is a power interruption and any thermostat call,
the control initiates a 90-sec blower only on period before starting
another cycle.
BLOWER OFF DELAY
ADJUSTMENT SWITCH
TEST/TWIN
SEC-1
3-AMP FUSE
COOL
HEAT
HOT SURFACE
INDUCER MOTOR
IGNITOR
CONNECTOR
CONNECTOR
Fig. 9—Control Board
EAC1
EAC2
A93053
24V THERMOSTAT
G
TERMINALS
R
Y
W
HUMIDIFIER TERMINAL
Com
(24-VAC 0.5 AMP MAX)
24V
HUM
LED OPERATION &
DIAGNOSTIC LIGHT
HARNESS CONNECTOR
24V TRANSFORMER SEC-2
SPARE 1
BLOWER SPEED
SELECTION TERMINALS
SPARE 2
EAC 1 (BLACK)
EAC-ELECTRONIC AIR CLEANER
TERMINALS (115-VAC 1.5 AMP MAX)
EAC 2 (WHITE)
115-VAC (L2) NEUTRAL
CONNECTION

1. Heating mode

When the wall thermostat "calls for heat," the R-W circuit
closes. The furnace control performs a self-check, verifies the
pressure switch contacts are open, and starts inducer motor.
a. Prepurge period—As the inducer motor comes up to speed,
the pressure switch contacts close to begin a 15-sec
prepurge period.
b. Ignitor warm-up—At the end of the prepurge period, the
ignitor is energized for a 17-sec ignitor warm-up period.
c. Ignition sequence—When the ignitor warm-up period is
completed, the gas valve opens, permitting gas flow to the
burners where it is ignited. After 5 sec, the ignitor is
de-energized and a 2-sec flame-sensing period begins.
d. HUM terminal is energized with the gas valve. See
accessories in the Electrical Connections section.
e. Flame-sensing—When burner flame is sensed, the control
begins the blower on delay period and continues holding
the gas valve open. If burner flame is not sensed, the
control closes the gas valve and repeats ignition cycle.
NOTE: Ignition sequence will repeat 3 additional time before a
lockout occurs. Lockout automatically resets after 3 hrs, or can be
manually reset by turning 115v off (not at thermostat) for 3 sec
minimum, then on again.
f. Blower on delay—Forty sec after burner flame is proven,
the blower motor is energized on heating speed. Simulta-
neously, the humidifier and electronic air cleaner terminals
(HUM and Com for humidifier, EAC-1 and EAC-2 for
electronic air cleaner) are energized. If jumper is on pin 6
and pin 9, blower on delay is 60 sec.
9
A93052