035-17438-001 Rev. A (901)
16
Unitary Products Group
Increase the blower speed to decrease the temperature rise;
decrease the blower speed to increase the rise.
All direct-drive blowers have multi-speed motors. The blower
motor speed taps are located in the control box in the blower
compartment.
You may select a heating speed and a cooling speed. They
may be the same speed or a different speed.
To use the same speed tap for heating and cooling, the heat
terminal and cool terminal must be connected using a jumper
wire and connected to the desired motor lead. Place all
unused motor leads on Park terminals. Two Park terminals
are provided.
Variable Speed Motors
The temperature rise, or temperature difference between the
return air and the heated air from the furnace, must be within
the range shown on the furnace rating plate and within the
application limitations shown in Table 3 on page 7.
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” or “C”, or “D”.
Pins “A” will provide the highest CFM and “D” the lowest
CFM. Refer to Table 6 on page 17 for CFM options.
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 18 of this instruction.
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.
COOLING AIRFLOW
The Cooling airflow is preset at the factory to provide approx-
imately 90% of the maximum CFM and must be adjusted in
the field to match the HVAC system at installation. Refer to
the outdoor unit installation instruction for the recommended
airflow and Table 6 on page 17.
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 cooing 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 programmed
cooling air flow for 60 seconds, with a 15 second coast to
stop.
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.
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, 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 and the fan-off timing may be
adjusted by setting the DIP switches located on the control
board as follows: (See Figure 12 and Table 5).
This continuous fan speed dip switch (switch 3) on the igni-
tion control has no effect on setting and should be left in the
“OFF” position, as continuous fan speed is determined by the
variable speed motor program.
Do not energize more than one motor speed at a
time or damage to the motor will result.
Table 5:
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 12 :
Typical Heat/Cool Speed Tap
Connections
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
