2. Cooling Mode
(See Fig. 30 for thermostat connections)
The thermostat closes the R-to-G-and-Y circuits. The R-to-Y
circuit starts the outdoor unit, and the R-to-G and Y circuits
start the furnace blower motor BLWM on COOL speed.
The electronic air cleaner terminal EAC-1 is energized with
115 vac when the blower motor BLWM is operating.
When the thermostat is satisfied, the R-to-G-and-Y circuits are
opened. The outdoor unit will stop, and the furnace blower
motor BLWM will continue operating on the COOL speed for
an additional 90 seconds. Cut jumper J2 to reduce the cooling
off-delay to 5 seconds. (See Fig. 33.)
3. Continuous Blower Mode
When the R-to-G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous-blower
speed (same as HEAT speed). Terminal EAC-1 is energized as
long as the blower motor BLWM is energized.
During
″
a call for heat,
″
the blower BLWM will stop during
igniter warm-up (17 seconds), ignition (7 seconds), and
blower-ON delay (66 seconds), allowing the furnace heat
exchangers to heat up more quickly, then restarts at the end of
the blower-ON delay period at HEAT speed.
In heating, the furnace control CPU will continue running the
blower motor BLWM at HEAT speed after the selected
blower-OFF delay period is completed.
When the thermostat
″
calls for cooling
″
, the blower motor
BLWM will operate at COOL speed. When the thermostat is
satisfied, the blower motor BLWM will operate an additional
90 seconds on COOL speed before reverting back to HEAT
speed. Jumper J2 can be can be cut to reduce the cooling
off-delay to 5 seconds. (See Fig. 33.)
When the R-to-G circuit is opened, the blower motor BLWM
will continue operating for an additional 5 seconds, if no other
function requires blower motor BLWM operation.
4. Heat Pump Mode
When installed with a heat pump, the furnace control auto-
matically changes the timing sequence to avoid long blower
off times during demand defrost cycles. When the R-to-W-
and-Y or R-to-W-and-Y-and-G circuits are energized the
furnace control CPU will continue to 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-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 signals disap-
pear, leaving the G signal, the blower motor BLWM will
continue running the blower motor BLWM at HEAT speed
after the selected blower-OFF delay period is completed.
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 at the control and not until all time delays are
completed.
NOTE:
Record the status code BEFORE opening the blower
access door and before shutting off power to the furnace. Opening
the blower access door will open the blower door switch and shut
off power within the furnace. When power to the furnace is shut
off by either method, the status code will be lost because the code
is not stored while power is removed for any reason.
To Begin Component Self-Test:
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.
Fig. 42—Example of Field Drain Attachment
A94054
OPEN STAND
PIPE FOR
A/C OR
HUMIDIFIER
DRAIN
TEE
TO OPEN
DRAIN
Fig. 43—Condensate Trap Heat Tape
A93036
CONDENSATE TRAP
WIRE TIE(S)
HEAT TAPE
(3 WRAPS MINIMUM)
35
