035-17468-001 Rev. A (801)
30
Unitary Products Group
HEATING AIRFLOW
The heating airflow has been preset at the factory to provide
maximum CFM. If a lesser CFM is required for a specific
HVAC system the “JUMPER” on the HEAT selection pins on
the CFM-Timer Board may be moved to tap “B”, “C”, or “D”.
Pin “A” will provide the highest CFM and “D” the lowest CFM
(Refer to Tables 9 or 10).
NOTE:
When changing jumper positions, make sure that the
jumper is pushed all the way on the pins. If the jumper is not
making good contact or is left off completely, the blower will
operate as if the jumper were in the “A” position.
NOTE:
Power to the blower must be removed for at least 4
seconds after a heat or cool tap selection change, in order for
the motor to recognize an adjustment.
The fixed blower on delay and adjustable blower-off delay will
function as described in the “OPERATION AND
MAINTENANCE" Section on Page 32 of this instruction.
COOLING AIRFLOW
The cooling airflow is preset at the factory to provide approxi-
mately 90 percent of the maximum CFM and must be field
adjusted to match the HVAC system at installation. Refer to
the outdoor unit installation instruction for the recommended
airflow for the cooling system.
The "DELAY" Tap should be set in the "B" position for a two-
stage condenser. This results in a 45 second off delay at 82%
of the programmed cooling airflow with a 15-second coast to
stop. It should be set in the "C" position for a system with a
TXV or solenoid valve. This results in a 45 second off delay at
75% of the programmed cooling airflow with a 15-second
coast to stop. It should be set in the "D" position for a system
without a TXV or solenoid valve. This results in a 60 second
off delay at 82% of the programmed cooling airflow with a 15-
second coast to stop. The "A" position is the factory setting
and is used for test purposes. With the delay set in the “A”
position, the blower will operate at 100% of the programed
cooling air flow for 60 seconds, with a 15 second coast to
stop.
ADJUSTMENT OF FAN-OFF CONTROL SETTINGS
This furnace is equipped with a time-on/time-off heating fan
control. The fan-on is fixed at 30 seconds. The fan-off delay is
factory set to 60 seconds (refer to Table 8 and Figure 40),
however, it is field-adjustable to 90, 120 or 180 seconds. The
fan-off setting must be long enough to adequately cool the
furnace, but not so long that cold air is blown into the heated
space.
The continuous fan speed dip switch (switch 3) on the ignition
control has no affect on setting and should be left in the off
position, as continuous fan speed is determined by the vari-
CONTINUOUS BLOWER
There are two modes of continuous blower operation. In one
mode the blower is controlled directly through the blower
motor. In the second mode the blower is controlled through
the ignition control. In the first mode, when the thermostat
fan-switch is set to the ON position a circuit is completed
between terminals “R” and “G” of the thermostat. The contin-
uous fan speed will be 63% of the high cool speed. If more air
is desirable the green wire labeled (G Cool Speed) may be
connected to the “G” terminal of the ignition control to achieve
HIGH COOL speed (DIP switch number 3 on the ignition con-
trol must be in the OFF position). The air cleaner and the
blower motor are energized through the ignition control or
directly through the motor.
INTERMITTENT BLOWER COOLING
On cooling/heating thermostats with fan switch, when the fan
switch is set in the auto position and the thermostat calls for
cooling, a circuit is completed between the R, Y and G termi-
nals. The motor is energized through the Y1 cool terminal
and runs on the speed selected on the CFM Timer board.
The fan off setting is fixed at 60 seconds for SEER enhance-
ment.
Table 8:
FAN CONTROL SETTINGS
IGNITION CONTROL
To Delay Fan-Off By:
Set Switch
1-2
60 Sec.
On-On
90 Sec.
Off-On
120 Sec.
On-Off
180 Sec.
Off-Off
FIGURE 40 :
Typical Heat/Cool Speed Tap
Connections (PSC Motor)
OFF
ON
SWITCH 3 SHOULD
BE LEFT IN “OFF”
POSITION
COOL
HEAT LO
HEAT HI
LINE
WI
W2
Y
R
G
B
FAN OFF
ADJUSTMENT
SWITCHES