Operating instructions

cycle. The blower motor BLWM will remain on until the
end of the prepurge period, then shut off for 24 seconds then
come back on at HEAT speed. When the W input signal
disappears, the furnace control begins a normal inducer
post-purge period and the blower remains running at HEAT
speed for the selected blower-OFF delay period then
switches to low-cool speed (same speed as FAN). If the R
to W-and-Y1-and-G signals disappear at the same time, the
blower motor BLWM will remain on for the selected
blower-OFF delay period. If the R to W-and-Y1 signals
disappear, leaving the G signal, the blower motor BLWM
will remain on for the selected blower-OFF delay period
then switch to continuous-blower speed.
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 the furnace control CPU will switch
to or turn on the blower motor BLWM at HEAT speed, and
begin a heating cycle. The blower motor BLWM will
remain on until the end of the prepurge period, then shut off
for 24 seconds then come back on at HEAT speed. When
the W input signal disappears, the furnace control begins a
normal inducer post-purge period and the blower switches
to COOL speed 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-G
signals disappear at the same time, the blower motor
BLWM will remain on for the selected blower-OFF delay
period. If the R to W-and-Y/Y2 or R to W-and-Y1-and-
Y/Y2 signals disappear, leaving the G signal, the blower
motor BLWM will remain on for the selected blower-OFF
delay period then switch to continuous-blower speed.
F. Component Test
NOTE: The furnace control component test allows all compo-
nents to run for a short time; except the gas valve and humidifier
terminal HUM are not energized for safety reasons. The EAC-1
terminal is energized when the blower is energized. This feature
helps diagnose a system problem in case of a component failure.
The component test feature will not operate if any thermostat
signal is present ant the control and not until all time delays are
completed.
To Begin Component Self-Test:
WARNING: Blower access panel door switch opens
115-v power to control center. No component operation
can occur. Caution must be taken when manually closing
this switch for service purposes. Failure to follow this
warning could result in electrical shock, personal injury,
or death.
1. Remove blower access door.
2. Disconnect the thermostat R lead from furnace control.
3. Manually close blower door switch.
4. For approximately 2 sec, short (jumper) the C
OM-24v
terminal on control to the TEST/TWIN 3/16-inch quick-
connect terminal on control until the LED goes out.
Remover jumper from terminals. (See Fig. 31.)
NOTE: If TEST/TWIN and C
OM-24v terminals are jumpered
longer than 2 sec, LED will flash rapidly and ignore component
test request.
Component test sequence is as follows:
d. LED will display previous status code 4 times.
e. Inducer motor starts and continues to run until Step g of
component test sequence.
f. After 7 seconds the hot surface igniter is energized for 15
sec., then off.
g. Blower motor operates on Continuous-FAN speed for 10
sec.
h. Blower motor operates on HEAT speed for 10 sec.
i. Blower motor operates on COOL speed for 10 sec.
j. Inducer motor stops.
5. Reconnect R lead to furnace control, remove tape from
blower door switch, and re-install blower door.
6. Operate furnace per instruction on outer door.
7. Verify furnace shut down by lowering thermostat setting
below room temperature.
8. Verify that furnace restarts by raising thermostat setting
above room temperature.
START-UP PROCEDURES
I. GENERAL
1. Furnace must have a 115-v power supply properly con-
nected and grounded.
NOTE: Proper polarity must be maintained for 115-v wiring. If
polarity is incorrect, control center LED status indicator light will
flash rapidly and furnace will not operate.
2. Thermostat wire connections at terminals R, W, G, and
Y/Y2 must be made at 24-v terminal block on furnace
control.
3. Natural gas service pressure must not exceed 0.5 psig
(14-in. wc), but must be no less than 0.16 psig (4.5-in. wc).
4. Blower access panel must be in place to complete 115-v
electrical circuit to furnace.
CAUTION: These furnaces are equipped with a manual
reset limit switch in burner box. This switch will open
and shut off power to gas valve if an overheat condition
(flame rollout) occurs in burner enclosure. Correct inad-
equate combustion-air supply or improper venting condi-
tion and reset switch. DO NOT jumper this switch.
Failure to follow this caution will result in intermittent
unit operation or performance satisfaction.
Before operating furnace, check flame rollout manual reset switch
for continuity. If necessary, press button to reset switch.
II. PRIME CONDENSATE TRAP WITH WATER
CAUTION: Condensate trap must be PRIMED or
proper draining may not occur. The condensate trap has 2
internal chambers which can ONLY be primed by pour-
ing water into the inducer drain side of condensate trap.
Failure to follow this caution will result in intermittent
unit operation or performance satisfaction.
1. Remove upper inducer housing drain connection cap. (See
Fig. 55.)
2. Connect field-supplied 1/2-in. ID tube to upper inducer
housing drain connection.
3. Insert field-supplied funnel into tube.
4. Pour 1 quart of water into funnel/tube. Water should run
through inducer housing, overfill condensate trap, and flow
into open field drain. (See Fig. 56.)
5. Remove funnel and tube from inducer housing and replace
drain connection cap and clamp.
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