Carrier WEATHERMAKER 8000 58WAV Installation, Start-Up And Operator'S Manual Download

Page: 13 / 24

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. Igniter warm-up—At the end of the prepurge period, the

igniter is energized for a 17-sec igniter warm-up period.

c. Ignition sequence—When the igniter warm-up period is

completed, the gas valve opens, permitting gas flow to the
burners where it is ignited. After 5 sec, the igniter 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 hr, or can be
manually reset by turning 115v off (not at thermostat) for 3 sec
minimum, then on again.

f. Blower on delay—Forty-five sec after burner flame is

proven, the blower motor is energized on heating speed.
Simultaneously, the humidifier and electronic air cleaner
terminals (HUM and C

-24V for humidifier, EAC-1 and

EAC-2 for electronic air cleaner) are energized. If jumper is
across PL 7-6 and PL 7-9.

g. Blower off delay—When the thermostat is satisfied, the

circuit between R-W is broken, de-energizing the gas valve

stopping gas flow to the burners. The blower motor and
EAC remain energized 90, 135, 180, or 225 sec (depending
on the blower off-time selection). The furnace is factory set
for a 135-sec blower off delay.

h. Post-purge—The inducer motor remains energized 5 sec

after the burners are extinguished. If jumper is across PL
7-6 and PL 7-9, the post-purge period is 15 sec.

2. Cooling mode

a. Single-Speed Outdoor Unit-See Figures 9,10 and 12.

The thermostat closes the R to G and Y circuits. The
R-Y/Y2 circuit starts the outdoor unit, and the R to G and
Y/Y2 circuits start the furnace blower motor on COOL
speed. Electronic air cleaner EAC-1 terminal is energized
with 115v whenever blower is operating.
When thermostat is satisfied, R to G and Y/Y2 circuits are
opened. The outdoor unit stops and the furnace blower
continues operating on COOL speed for an additional 90
sec. Jumper Y/Y2 to DHUM on the furnace control to
reduce the cooling off-delay to 3 sec from 90. See figure
15.

b. Two-Speed Outdoor Unit without Thermidistat-See Fig.

14.

The thermostat closes the R to G and Y1 circuits for low
cooling and the R to G, Y1 and Y/Y2 circuits for high
cooling. The R to Y1 circuit starts the outdoor unit on low
cooling and the R to G and Y1 circuits start the furnace
blower on FAN speed. The R to Y1 and Y2 circuits start
the outdoor unit on high cooling and the R to G, Y1 and Y2
circuits start the furnace blower on COOL speed.
If the R to Y2 circuit opens with the R to G and Y1 circuits
still closed, the outdoor unit will drop to low cooling and
the furnace control will drop the blower speed to FAN.

Fig. 15—Furnace Control

A99417

1
2
3
4
5

135
180
225

3-AMP FUSE

HUMIDIFIER TERMINAL

(24-VAC 0.5 AMP MAX)

LED OPERATION &

DIAGNOSTIC LIGHT

HARNESS CONNECTOR

24-V TRANSFORMER SEC-2

SPARE-1