ICP 9MAC/E series Troubleshooting manual - page 6
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3.
Cooling Off-Delay -
When the “call for cooling” is satisfied
and there is a demand for dehumidification, the cooling blower-
off delay is decreased from 90 seconds to 5 seconds.
SUPER-DEHUMIDIFY MODE
Super-Dehumidify mode can only be entered if the furnace control is
in the Dehumidification mode and there is a demand for
dehumidification. The cooling operation described in the Cooling
Mode section above also applies to Super Dehumidify Mode. The
exceptions are listed below:
1.
Low Cooling
– When the R to Y1 circuit is closed, R to G
circuit is open, and there is a demand for dehumidification, the
furnace blower motor BLWM will drop the blower airflow to
65% of low-cooling airflow for a maximum of 10 minutes each
cooling cycle or until the R to G circuit closes or the demand for
dehumidification is satisfied. Low-cooling airflow is the true
on-board CF selection as shown in Table 1.
2.
High Cooling
– When the R to Y/Y2 circuit is closed, R to G
circuit is open, and there is a demand for dehumidification, the
furnace blower motor BLWM will drop the blower airflow to
65% of high-cooling airflow for a maximum of 10 minutes each
cooling cycle or until the R to G circuit closes or the demand for
dehumidification is satisfied. High-cooling airflow is based on
the A/C selection shown in Table 1.
3.
Cooling Off-Delay
– When the “call for cooling” is satisfied
and there is a demand for dehumidification, the cooling blower-
off delay is decreased from 90 seconds to 5 seconds.
CONTINUOUS BLOWER MODE
When the R to G circuit is closed by the thermostat, the blower motor
BLWM will operate at continuous blower airflow. Continuous
blower airflow selection is initially based on the CF selection shown
in Table 1. Factory default is shown in Table 1. 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 continuous blower airflow, minimum-heat
airflow, or the midrange airflow, whichever is lowest. The blower
motor BLWM will remain ON until the main burners ignite then shut
OFF and remain OFF for the blower-ON delay (45 seconds in
intermediate-heat, and 25 seconds in maximum-heat), allowing the
furnace heat exchangers to heat up more quickly, then restarts at the
end of the blower-ON delay period at modulating or maximum-heat
airflow respectively.
The blower motor BLWM will revert to continuous-blower airflow
after the heating cycle is completed. When the thermostat satisfies,
the furnace control CPU will drop the blower motor BLWM to
minimum-heat airflow during the selected blower-OFF delay period
before transitioning to continuous-blower airflow.
When the thermostat "calls for low-cooling", the blower motor
BLWM will switch to low-cooling airflow. When the thermostat is
satisfied, the blower motor BLWM will operate an additional 90
seconds at low-cooling airflow before transitioning back to
continuous-blower airflow.
When the thermostat "calls for high-cooling", the blower motor
BLWM will switch to high cooling airflow. When the thermostat is
satisfied, the blower motor BLWM will operate an additional 90
seconds at high-cooling airflow before transitioning back to
continuous-blower airflow.
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.
HEAT PUMP DEFROST
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 W/W1 is energized along with Y1
or Y/Y2, the furnace control CPU will transition to or bring on the
blower motor BLWM at cooling airflow, minimum-heat airflow, or
the midrange airflow, whichever is lowest. 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
modulating heat airflow. When the W/W1 input signal disappears,
the furnace control begins a normal inducer post-purge period while
changing the blower airflow. If Y/Y2 input is still energized the
furnace control CPU will transition the blower motor BLWM airflow
to cooling airflow. If Y/Y2 input signal disappears and the Y1 input
is still energized the furnace control CPU will transition the blower
motor BLWM to low-cooling airflow. If both the Y1 and Y/Y2
signals disappear at the same time, the blower motor BLWM will
remain on at minimum-heat airflow for the selected blower-OFF
delay period. At the end of the blower-OFF delay, the blower motor
BLWM will shut OFF unless G is still energized, in which case the
blower motor BLWM will operate at continuous blower airflow.
COMPONENT TEST
The furnace features a component test system to help diagnose a
system problem in the case of a component failure. To initiate the
component test procedure, ensure that there are no thermostat inputs
to the control and all time delays have expired. Turn on setup switch
SW1-6. (See Appendix A)
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:
1. The furnace control CPU turns the inducer motor IDM ON at
medium speed and keeps it ON through step 4.
2. The furnace control CPU will test communication with the
modulating gas valve GV.
3. After waiting 15 seconds the furnace control CPU turns the hot
surface igniter ON for 15 seconds, then OFF.
4. The furnace control CPU then turns the blower motor BLWM
on at midrange airflow for 15 seconds, then OFF.
5. After shutting the blower motor OFF the furnace control CPU
shuts the inducer motor IDM OFF.
Note:
The EAC terminals are energized when the blower is
operating.
After the component test is completed, 1 or more status codes
(Heartbeat, 2 + 5, 3 + 5, 4 + 1, or 4 + 2) will flash. See Service Label
on control door or Service/Status Code Instructions for explanation
of status codes.
Note:
To repeat component test, turn setup switch SW1-6 to OFF
and then back ON.
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