b. R-W/W1 with R-Y/Y2 and R-G signals terminated—
The blower continues to operate completing a normal
blower off delay.
11. Post purge—The inducer continues operating for 15 sec
after gas valve is de-energized.
VII.
CONTINUOUS FAN MODE
1. Operating with continuous fan only.
a. Call for continuous fan—The thermostat closes R-G
circuit.
b. Blower on—The blower starts immediately.
NOTE:
The blower starts at approximately 400-500 RPM. After
20 sec, the motor is turned off for 1/10 of a sec where a coast down
calibration is done to evaluate resistance of the conditioned air
duct system. The microprocessor then determines blower RPM
required to provide proper airflow for heating mode.
NOTE:
The continuous fan speed is the same as low-heat speed
unless it is field adjusted to another desired airflow. See Continu-
ous Fan Setup Switches section. There is also a chart on wiring
diagram. (See Fig. 23.)
c. Electronic Air Cleaner—The EAC-1 terminal is ener-
gized whenever blower operates, regardless of operating
mode.
2. Operating with continuous fan (R-G) and call for heat
(R-W/W1) is received—Same as heat pump mode except
blower on delay is 10 sec less than the heat mode. After call
for heat (R-W/W1) is terminated, the blower remains
operating at low-heat speed for selected blower off delay
before resuming continuous fan speed.
3. Operating with continuous fan (R-G) and call for cool-
ing (R-Y/Y2) is received—See Cooling Mode section.
After call for cooling (R-Y/Y2) is terminated, the blower
remains operating at cooling speed for 90 sec before
resuming continuous fan speed.
VIII.
COMPONENT TEST
All components are functionally operated except gas valve with
component test feature.
This feature helps diagnose a system problem in case of a
component failure.
NOTE:
Setup switch SW-1 MUST be in OFF position or Fault
Code 22 (setup error) will occur.
NOTE:
NO thermostat signal may be present at control center,
and all blower time delay off periods must be completed.
To initiate component test feature, proceed with the following:
1. Leave 115-v power to furnace turned on.
2. Remove main furnace door.
3. Remove blower access panel.
4. Turn setup switch SW-6 to ON position.
5. Manually close blower access panel door switch.
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 personal injury or death.
When items 1-5 have been completed, the following will occur:
1. The control center goes through a brief self test. This self
test takes approximately 2 sec to complete. After door
switch is closed, red (microprocessor) LED briefly comes
on. Then green LED comes on for 1 sec, followed by 1 sec
where both green and yellow LEDs are on. During this time,
the microprocessor is checking itself.
2. Inducer motor operates for 20 sec at low speed, operates 20
sec at high speed, then turns off.
3. Hot surface ignitor is energized for 15 sec, then de-
energized.
4. Main blower motor operates for 20 sec at low speed,
operates for 20 sec at high speed, then turns off.
5. After component operation test is completed, 1 or more
fault codes (11, 22, 41, or 42) will flash. See service label
on back of main furnace door for explanation of fault codes.
NOTE:
To repeat component test, turn setup switch SW-6 to OFF
and then back to ON.
After component test, perform the following:
1. Release blower panel access door switch and turn setup
switch SW-6 to OFF position.
2. If applicable, replace blower access panel and check LED
status by removing plug in blower access panel.
3. Reinstall main furnace door if all LEDs are off, indicating
furnace is ready to operate when a signal from thermostat is
received.
IX.
BYPASS HUMIDIFIER MODE
When setup switch SW-3 BPH is in ON position, RPM calculated
for low heat is multiplied by 1.15 for all furnace model sizes. This
compensates for increased return-air temperature caused by by-
passed air supply.
X.
DEHUMIDIFICATION MODE
If dehumidification input is energized with a 24-vac input, RPM
calculated for cooling and continuous fan is multiplied by 0.85 for
all furnace model sizes. This compensates for high humidity
conditions during cooling operation.
XI.
ZONE MODE
When setup switch SW-5 MZ is in ON position, blower motor
control is the same as above except with the following exceptions:
1. While blower is operating in either low heat or continuous
fan, the coast down calibration is performed once a minute
to update blower RPM for zone damper position changes
during a given cycle unless the blower pulse width to
blower motor is greater than 60 percent. This prevents
nuisance faults from occurring when a high continuous fan
CFM has been selected.
2. While blower is operating in either high heat or cooling,
blower pulse width to blower motor is frozen when blower
RPM is within 10 percent of calculated blower RPM for 5
sec.
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 fault indicator light flashes
rapidly and furnace does not operate.
2. Thermostat wire connections at terminals R, W/W1, G, and
Y/Y2 must be made at 24-v terminal block on control
center.
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 24-v
electrical circuit to furnace.
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