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BLWM is operating. When the thermostat is satisfied, the
R
-
G and
-
Y circuit is opened. The outdoor unit stops, and
the furnace blower BLWM and electronic air cleaner
terminal EAC- -1 will remain energized for an additional
90 seconds. Remove J2 Jumper to reduce the cooling
off- -delay to 5 seconds. (See Fig. 38)
3. Continuous Blower Mode
When the R
-
G circuit is closed by the thermostat, the
blower motor BLWM will operate at FAN tap (See Fig.
38). Terminal EAC- -1 is energized as long as the blower
motor BLWM is energized. During a call for heat, the
furnace control CPU will transition the blower motor
BLWM to FAN tap. The blower motor BLWM will
remain ON until the main burners ignite then shut OFF
and remain OFF for 25 seconds before coming back on at
HEAT tap. The blower motor BLWM will revert to FAN
tap after the heating cycle blower off- -delay is completed.
When the thermostat "calls for cooling", the blower motor
BLWM will switch to operate at COOL tap. When the
thermostat is satisfied, the blower motor BLWM will
operate an additional 90 seconds at cooling airflow before
transitioning back to FAN tap. When the R
opened, the blower motor BLWM will continue operating
for an additional 5 seconds, if no other function required
blower motor BLWM operation.
4. Heat Pump:
When installed with a heat pump, the
furnace control automatically changes the timing sequence
to avoid long blower off times during demand defrost
cycles. Whenever the R
Wcircuit is closed along with the
-
R
Y circuit, the furnace control CPU will transition to or
-
bring on the blower motor BLWM at COOL tap. The
blower motor BLWM will remain on until the main
burners ignite then shut OFF and remain OFF for 25
seconds before coming back on at HEAT tap. When the
R
W connection is opened, the furnace control begins a
-
normal inducer post- -purge period while changing the
blower airflow. If R
-
Y circuit is still closed, the furnace
control CPU will transition the blower motor BLWM
airflow to COOL tap. If R
motor BLWM will remain on HEAT tap for the selected
blower- -OFF delay period. At the end of the blower- -OFF
441 01 1501 04
-
G circuit is
G circuit is open, the blower
-
Specifications are subject to change without notice.
delay, the blower motor BLWM will shut OFF unless R
is circuit is closed, in which case the blower motor BLWM
will operate at FAN tap.
5. Component Test: The furnace features a component test
feature to help diagnose a system problem in the case of a
component failure. To initiate the component test
sequence, shut OFF the room thermostat or disconnect the
R thermostat lead. Briefly short the TEST/TWIN terminal
to the C terminal. Status LED will flash most recent code 4
times and then turn ON the inducer motor.
The inducer motor will run for the entire component test.
The hot surface ignitor, blower motor fan speed, blower
motor- -heat speed, and blower motor- -cool speed will be
turned ON for 10- -15 seconds each. Gas Valve and
Humidifier will not be turned on. (See Fig. 38).
NOTE: The component test feature will not operate if the control
is receiving any thermostat signals or until all time delays have
.
expired
The component test sequence is as follows:
Sequence of Operation - - Fan Only
1. Inducer relay ON 50% ULN80 for 15 seconds then
proceed to Step 2. Inducer to remain ON throughout the
test.
2. HSI relay ON for 15 sec., then OFF.
3. Blower motor FAN Speed for 10 sec., then OFF.
4. Blower motor HEAT Speed for 10 sec., then OFF.
5. Blower motor COOL Speed for 10 sec., then OFF.
6. Inducer OFF, end of test
NOTE: The EAC terminals are energized when the blower is
operating.
Wiring Diagrams
Refer to Fig. 38 for wiring diagram.
Troubleshooting
Refer to the service label. (Fig. 35), wiring diagram (Fig. 38), and
the Service Guide (Page 37) can be a useful tool in isolating
furnace operation problems. The Guide will help to identify the
problem or failed component. After replacing any component,
verify correct operation sequence.
-
G
35
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